CVE-2025-31877

Executive Summary

CVE-2025-31877 is a Missing Authorization vulnerability in the RestroPress WordPress plugin by Magnigenie, affecting versions up to and including 3.2.8. This flaw allows an unauthenticated attacker to exploit incorrectly configured access control security levels, potentially leading to unauthorized actions within the plugin's functionality. The vulnerability has a CVSS score of 4.3 (Medium), with a low EPSS score of 0.0% indicating limited active exploitation at the time of analysis. No public proof-of-concept (PoC) code or patch is currently available, making this a high-priority issue for defenders to monitor and mitigate through access controls and monitoring.

Supply Chain & Package Security

This vulnerability resides in a WordPress plugin ecosystem. Organizations using RestroPress should verify their version and apply any available updates from the WordPress plugin repository or vendor. Since no patch is available, consider disabling the plugin or implementing strict web application firewall (WAF) rules to block exploitation attempts.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
• Base Score: 4.3 (Medium)
• Attack Vector: Network (AV:N) – Exploitable remotely.
• Attack Complexity: Low (AC:L) – No special conditions required.
• Privileges Required: None (PR:N) – No authentication needed.
• User Interaction: None (UI:N) – No user action required.
• Scope: Unchanged (S:U) – Impact confined to the vulnerable component.
• Confidentiality Impact: None (C:N) – No data exposure.
• Integrity Impact: Low (I:L) – Limited modification of data or settings.
• Availability Impact: None (A:N) – No denial of service.

Threat Level: Medium. The low EPSS score suggests limited active exploitation, but the lack of a patch and the potential for unauthorized access to plugin features warrants immediate attention.

Deep Dive & Mechanics

The vulnerability stems from a Missing Authorization check (CWE-862) in the RestroPress plugin. The plugin likely exposes certain REST API endpoints or AJAX actions that perform sensitive operations (e.g., modifying menu items, orders, or settings) without verifying the user's capabilities or authentication status. An unauthenticated attacker can send crafted HTTP requests to these endpoints, bypassing access controls due to missing current_user_can() or similar permission checks.

Attack Vector:

1. The attacker identifies a vulnerable endpoint (e.g., /wp-json/restropress/v1/order/update or an AJAX action like restropress_update_menu).
2. The attacker sends a POST/GET request with malicious parameters to modify data or trigger unintended actions.
3. The plugin processes the request without verifying the user's role or authentication, leading to unauthorized changes.

Impact: An attacker could potentially modify restaurant menus, change order statuses, or alter plugin settings, depending on the specific missing authorization check. This could lead to data integrity issues and business disruption for restaurants using the plugin.

Vulnerable vs. Patched Code

Since no patch is available, the vulnerable code pattern is hypothesized based on common WordPress plugin authorization flaws.

Vulnerable Code (Hypothetical):

// In a RestroPress AJAX handler or REST endpoint
add_action('wp_ajax_nopriv_restropress_update_menu', 'restropress_update_menu_callback');
function restropress_update_menu_callback() {
    // Missing current_user_can() check
    $menu_id = $_POST['menu_id'];
    $menu_data = $_POST['menu_data'];
    // Update menu without authorization
    update_post_meta($menu_id, '_menu_data', $menu_data);
    wp_send_json_success();
}

Patched Code (Hypothetical):

add_action('wp_ajax_nopriv_restropress_update_menu', 'restropress_update_menu_callback');
function restropress_update_menu_callback() {
    // Added authorization check
    if (!current_user_can('edit_restropress_menus')) {
        wp_send_json_error('Unauthorized', 403);
        return;
    }
    $menu_id = $_POST['menu_id'];
    $menu_data = $_POST['menu_data'];
    update_post_meta($menu_id, '_menu_data', $menu_data);
    wp_send_json_success();
}

Exploitation & Lab Setup

Red Team (Exploitation)

Prerequisites:

• A WordPress site with RestroPress <= 3.2.8 installed and active.
• Network access to the target site.

Exploitation Steps:

1. Identify Vulnerable Endpoint: Use a tool like Burp Suite or curl to enumerate AJAX actions or REST routes. Look for actions without nopriv_ prefix that should require authentication but don't.
2. Craft Exploit Request: Send a POST request to the vulnerable endpoint with malicious parameters.

   curl -X POST https://target.com/wp-admin/admin-ajax.php \
        -d 'action=restropress_update_menu&menu_id=123&menu_data={"name":"Hacked Menu"}'
   

3. Verify Impact: Check if the menu was modified without authentication.

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 starting with restropress_ from unauthenticated users.
• Look for HTTP 200 responses to unauthorized POST requests to plugin endpoints.

Mitigation:

• Disable the RestroPress plugin until a patch is released.
• Implement a Web Application Firewall (WAF) rule to block requests to known vulnerable endpoints.
• Use a WordPress security plugin to enforce authentication on AJAX actions.

Indicators of Compromise (IOCs)

• Network IOCs:
  • POST requests to /wp-admin/admin-ajax.php with action=restropress_* parameters from unauthenticated sources.
  • Unusual HTTP 200 responses to unauthorized plugin endpoints.
• File IOCs:
  • Modified menu or order data in the WordPress database (e.g., wp_postmeta table entries for _menu_data).
• Log IOCs:
  • WordPress debug log entries showing unauthorized access attempts to plugin functions.

Detection Engineering

YARA Rule

rule Detect_RestroPress_Missing_Auth {
    meta:
        description = "Detects exploitation attempts of CVE-2025-31877 in RestroPress plugin"
        author = "Valters IT"
        date = "2025-04-17"
        reference = "CVE-2025-31877"
    strings:
        $ajax_action = "restropress_" nocase
        $admin_ajax = "admin-ajax.php" nocase
        $wp_json = "/wp-json/restropress/" nocase
    condition:
        any of ($ajax_action) and any of ($admin_ajax, $wp_json)
}

Sigma Rule

title: CVE-2025-31877 RestroPress Missing Authorization Exploitation
id: 8a3f7c2e-5d1b-4a9f-8c6e-2b1d3f4a5c6e
status: experimental
description: Detects unauthenticated POST requests to RestroPress AJAX endpoints
author: Valters IT
date: 2025-04-17
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'POST'
        cs-uri-query|contains: 'admin-ajax.php'
        cs-uri-query|contains: 'action=restropress_'
    condition: selection
falsepositives:
    - Legitimate authenticated admin actions (rare)
level: medium

Suricata Rule

alert http any any -> any any (msg:"CVE-2025-31877 RestroPress Missing Authorization Exploitation"; flow:to_server,established; content:"POST"; http_method; content:"admin-ajax.php"; http_uri; content:"action=restropress_"; http_client_body; classtype:attempted-admin; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable the RestroPress plugin if it is not critical to operations.
2. Implement a WAF rule to block POST requests to admin-ajax.php with action parameters starting with restropress_ from unauthenticated users.
3. Monitor logs for exploitation attempts and block offending IPs.

Long-term Fix:

• Apply the official patch from Magnigenie once released.
• Update to the latest version of RestroPress (if a patched version becomes available).
• Conduct a security audit of all WordPress plugins for similar authorization flaws.

Workaround:

• Use a WordPress security plugin (e.g., Wordfence) to enforce authentication on AJAX actions.
• Restrict access to admin-ajax.php via .htaccess for unauthenticated users (may break legitimate functionality).

Valters IT