CVE-2025-12366

Executive Summary

CVE-2025-12366 is an Insecure Direct Object Reference (IDOR) vulnerability affecting the Page Builder: Pagelayer – Drag and Drop website builder plugin for WordPress in all versions up to and including 2.0.5. The flaw resides in the pagelayer_replace_page function, which lacks proper validation on a user-controlled key. This allows authenticated attackers with Author-level access or higher to replace media files belonging to other users, including administrators. The vulnerability has a CVSS score of 4.3 (Medium) and an EPSS score of 0.0%, indicating low exploitation probability in the wild. No public proof-of-concept or exploit code is currently available, and no patch has been released by the vendor.

Supply Chain & Package Security

This vulnerability is specific to the WordPress ecosystem and the Pagelayer plugin. It does not affect NPM, PyPI, Go, or Ruby packages. The risk is limited to WordPress sites running the vulnerable plugin version.

CVSS Breakdown & Threat Level

• CVSS Score: 4.3 (Medium)
• Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N
• Attack Vector: Network
• Attack Complexity: Low
• Privileges Required: Low (Author-level)
• User Interaction: None
• Scope: Unchanged
• Confidentiality Impact: None
• Integrity Impact: Low (unauthorized file replacement)
• Availability Impact: None

The threat level is considered Medium due to the low privileges required and the potential for integrity impact. However, the lack of public exploits and low EPSS score reduces immediate risk.

Deep Dive & Mechanics

The vulnerability is an Insecure Direct Object Reference (IDOR) in the pagelayer_replace_page function. This function is used to replace page content or media files. The flaw occurs because the function accepts a user-controlled key (likely a post ID or media attachment ID) without verifying that the authenticated user owns or has permission to modify the target object.

Attack Flow:

1. An attacker authenticates with Author-level privileges.
2. The attacker crafts a request to the pagelayer_replace_page function, specifying a target media file ID belonging to another user (e.g., an administrator).
3. The function processes the request without checking ownership, allowing the attacker to replace the media file with malicious content.
4. This could lead to defacement, phishing, or other malicious activities if the replaced file is used in critical areas.

The vulnerability is classified under CWE-639 (Authorization Bypass Through User-Controlled Key). The missing validation on the key allows unauthorized access to resources.

Vulnerable vs. Patched Code

Since no patch is available, the vulnerable code is presumed to be in the pagelayer_replace_page function. A patched version would include an ownership check.

Vulnerable Code (Conceptual):

function pagelayer_replace_page() {
    $post_id = $_POST['post_id'];
    // No ownership check
    wp_update_post(array('ID' => $post_id, 'post_content' => $_POST['content']));
}

Patched Code (Conceptual):

function pagelayer_replace_page() {
    $post_id = $_POST['post_id'];
    $post = get_post($post_id);
    if ($post->post_author != get_current_user_id() && !current_user_can('edit_others_posts')) {
        wp_die('Unauthorized');
    }
    wp_update_post(array('ID' => $post_id, 'post_content' => $_POST['content']));
}

Exploitation & Lab Setup

Red Team

Prerequisites:

• WordPress instance with Pagelayer plugin version <= 2.0.5.
• Authenticated user with Author-level privileges.
• Knowledge of a target media file ID (e.g., from another user's upload).

Exploitation Steps:

1. Log in as an Author.
2. Identify a target media file ID (e.g., via media library enumeration).
3. Send a POST request to the WordPress AJAX endpoint:

   POST /wp-admin/admin-ajax.php
   Content-Type: application/x-www-form-urlencoded
   
   action=pagelayer_replace_page&post_id=TARGET_MEDIA_ID&content=NEW_CONTENT
   

4. The media file is replaced with the attacker's content.

Note: No public exploit code is available. The above is a conceptual demonstration.

Blue Team

Detection:

• Monitor AJAX requests to admin-ajax.php with the pagelayer_replace_page action.
• Alert on requests where the post_id parameter does not match the user's own posts.
• Review logs for unusual file replacement activities.

Hunting:

• Search for pagelayer_replace_page in web server logs.
• Correlate with user IDs and post IDs to detect unauthorized access.

Indicators of Compromise (IOCs)

• Network:
  • POST requests to /wp-admin/admin-ajax.php with action=pagelayer_replace_page.
  • Unusual post_id values in AJAX requests from Author-level users.
• File System:
  • Modified media files in wp-content/uploads/ with unexpected content.
  • Changes to post content that do not match user permissions.
• Logs:
  • WordPress debug logs showing pagelayer_replace_page calls with mismatched user IDs.

Detection Engineering

YARA Rule

rule CVE_2025_12366_Pagelayer_IDOR {
    meta:
        description = "Detects exploitation attempts of CVE-2025-12366 in Pagelayer plugin"
        author = "Valters IT"
        date = "2025-04-01"
        reference = "CVE-2025-12366"
    strings:
        $ajax_action = "pagelayer_replace_page"
        $post_id_param = "post_id="
    condition:
        $ajax_action and $post_id_param
}

Sigma Rule

title: Pagelayer IDOR Exploitation Attempt
id: 8a9b7c6d-5e4f-3a2b-1c0d-9e8f7a6b5c4d
status: experimental
description: Detects attempts to exploit CVE-2025-12366 via AJAX requests
author: Valters IT
date: 2025-04-01
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: POST
        cs-uri-query|contains: 
            - "action=pagelayer_replace_page"
            - "post_id="
    condition: selection
falsepositives:
    - Legitimate plugin usage by administrators
level: medium

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (
    msg:"CVE-2025-12366 Pagelayer IDOR Exploitation Attempt";
    flow:to_server,established;
    content:"POST"; http_method;
    content:"/wp-admin/admin-ajax.php"; http_uri;
    content:"action=pagelayer_replace_page"; http_client_body;
    content:"post_id="; http_client_body;
    sid:10000001;
    rev:1;
    reference:cve,2025-12366;
    classtype:attempted-user;
    priority:2;
)

Remediation & Mitigation

Immediate Actions:

1. Disable the Pagelayer plugin until a patch is released.
2. Restrict Author-level permissions to prevent exploitation.
3. Monitor logs for suspicious AJAX requests.

Long-term Fix:

• Apply the vendor patch when available.
• Implement a Web Application Firewall (WAF) rule to block pagelayer_replace_page requests from non-admin users.
• Conduct a security audit of the plugin code.

Workaround:

• Use a custom plugin or code snippet to add ownership checks to the pagelayer_replace_page function.

Valters IT