CVE-2025-31836

Executive Summary

CVE-2025-31836 is a Missing Authorization vulnerability in the WordPress plugin Review Manager by matthewrubin, affecting versions up to and including 2.6.0. This flaw allows unauthenticated attackers to exploit incorrectly configured access control security levels, potentially leading to unauthorized data access or manipulation. The vulnerability has a CVSS score of 5.3 (Medium) and an EPSS score of 0.0%, indicating low exploitation likelihood currently, but the lack of a patch makes it a persistent risk for WordPress sites using this plugin.

Supply Chain & Package Security

This vulnerability resides in a WordPress plugin distributed via the official WordPress plugin repository. Since no patch is available, site administrators must consider removing or replacing the plugin to mitigate risk. The plugin is not available on NPM, PyPI, Go, or Ruby ecosystems.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
• Base Score: 5.3 (Medium)
• Attack Vector: Network
• Attack Complexity: Low
• Privileges Required: None
• User Interaction: None
• Scope: Unchanged
• Confidentiality Impact: Low
• Integrity Impact: None
• Availability Impact: None

The threat level is Medium due to the low complexity and no required privileges, but the impact is limited to confidentiality.

Deep Dive & Mechanics

The vulnerability stems from missing authorization checks in the Review Manager plugin's AJAX handlers or REST endpoints. The plugin likely fails to verify user capabilities before processing requests, allowing unauthenticated users to access or modify review data. The exact vulnerable endpoint is not publicly documented, but typical patterns include:

• wp_ajax_* hooks without current_user_can() checks
• REST API routes missing permission callbacks
• Direct database queries without nonce verification

Attackers can exploit this by sending crafted HTTP requests to the WordPress installation, bypassing access controls to read or manipulate review entries.

Vulnerable vs. Patched Code

Since no patch is available, we can only hypothesize the vulnerable code pattern:

Vulnerable Code (hypothetical):

add_action('wp_ajax_nopriv_get_reviews', 'get_reviews_callback');
function get_reviews_callback() {
    // Missing authorization check
    $reviews = $wpdb->get_results("SELECT * FROM wp_reviews");
    echo json_encode($reviews);
    wp_die();
}

Patched Code (hypothetical):

add_action('wp_ajax_nopriv_get_reviews', 'get_reviews_callback');
function get_reviews_callback() {
    if (!current_user_can('edit_posts')) {
        wp_die('Unauthorized', 403);
    }
    $reviews = $wpdb->get_results("SELECT * FROM wp_reviews");
    echo json_encode($reviews);
    wp_die();
}

Exploitation & Lab Setup

Red Team (Attack Simulation)

Prerequisites:

• WordPress installation with Review Manager <= 2.6.0
• No authentication required

Exploitation Steps:

1. Identify the vulnerable endpoint (e.g., /wp-admin/admin-ajax.php?action=rm_get_reviews)
2. Send a crafted request:

curl -X POST http://target/wp-admin/admin-ajax.php \
  -d "action=rm_get_reviews&nonce=123" \
  -H "User-Agent: Mozilla/5.0"

3. If successful, the response will contain review data in JSON format.

Note: No public exploit code is available; this is a hypothetical demonstration.

Blue Team (Defense & Detection)

Detection:

• Monitor for unusual AJAX requests to admin-ajax.php with action parameters related to Review Manager (e.g., rm_*)
• Look for requests from unauthenticated users to endpoints that should require authentication

Mitigation:

• Disable or remove the plugin immediately
• Implement Web Application Firewall (WAF) rules to block requests to known vulnerable endpoints
• Apply virtual patching via security plugins

Indicators of Compromise (IOCs)

• Network IOCs:

  • HTTP POST requests to /wp-admin/admin-ajax.php with action=rm_* parameters
  • Unusual JSON responses containing review data from unauthenticated sources

• File IOCs:

  • Presence of review-manager plugin directory in /wp-content/plugins/
  • Modified or new files in the plugin directory indicating exploitation attempts

• Log IOCs:

  • WordPress debug logs showing unauthorized access attempts to AJAX handlers
  • Web server logs with 200 responses to admin-ajax.php from unknown IPs

Detection Engineering

YARA Rule

Sigma Rule

Suricata Rule

Remediation & Mitigation

Immediate Actions:

1. Disable the plugin: Deactivate and delete the Review Manager plugin from all WordPress installations.
2. Virtual Patching: Use a WAF to block requests containing action=rm_ in POST data to admin-ajax.php.
3. Monitor Logs: Review web server and WordPress logs for any signs of exploitation.

Long-term Solutions:

• Replace the plugin with an actively maintained alternative that includes proper authorization checks.
• Implement a WordPress security plugin (e.g., Wordfence, Sucuri) to provide additional layers of protection.
• Regularly audit all installed plugins for known vulnerabilities and ensure they are patched.

Patch Status: No official patch is available. The vendor (matthewrubin) has not released a fix. Users are advised to remove the plugin entirely.

Valters IT
Securing Digital Frontiers