CVE-2025-22740

Executive Summary

CVE-2025-22740 is a Missing Authorization vulnerability in the Sensei LMS WordPress plugin by Automattic, affecting versions from n/a through 4.24.4. This flaw allows an unauthenticated attacker to exploit incorrectly configured access control security levels, potentially leading to unauthorized access to sensitive data or functionality. The vulnerability has a CVSS score of 5.3 (Medium) and an EPSS score of 0.0%, indicating low exploitation likelihood at this time. No public proof-of-concept or exploit code has been released, and no official patch is available.

Supply Chain & Package Security

This vulnerability affects the WordPress plugin ecosystem, specifically the Sensei LMS plugin distributed via the official WordPress plugin repository. Organizations using this plugin should treat it as a supply chain risk, as the vulnerable component is a third-party extension. No known malicious packages or backdoored versions have been reported.

CVSS Breakdown & Threat Level

• CVSS Score: 5.3 (Medium)
• Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
• 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 low confidentiality loss.

Deep Dive & Mechanics

The vulnerability resides in the Sensei LMS plugin's access control mechanisms. The plugin fails to properly validate user permissions when accessing certain REST API endpoints or administrative functions. Specifically, the sensei-lms plugin uses incorrect capability checks or omits them entirely, allowing unauthenticated users to trigger actions that should require higher privileges.

Root Cause: The plugin uses current_user_can() checks inconsistently or with incorrect capability names, leading to authorization bypass. For example, a function intended for administrators may be callable by any user or even unauthenticated visitors.

Attack Vector: An attacker can send crafted HTTP requests to the WordPress site's REST API or AJAX handlers, exploiting the missing authorization to read sensitive data (e.g., course content, student progress, or settings).

Vulnerable vs. Patched Code

Since no official patch is available, the following is a hypothetical fix based on common WordPress authorization patterns.

Vulnerable Code (sensei-lms <= 4.24.4):

// Example of missing authorization in a REST endpoint
add_action('rest_api_init', function () {
    register_rest_route('sensei-lms/v1', '/sensitive-data', array(
        'methods' => 'GET',
        'callback' => 'get_sensitive_data',
        'permission_callback' => '__return_true' // Vulnerable: allows all
    ));
});

Patched Code (Hypothetical):

add_action('rest_api_init', function () {
    register_rest_route('sensei-lms/v1', '/sensitive-data', array(
        'methods' => 'GET',
        'callback' => 'get_sensitive_data',
        'permission_callback' => function () {
            return current_user_can('manage_sensei'); // Proper capability check
        }
    ));
});

Exploitation & Lab Setup

Red Team (Exploitation)

Prerequisites:

• Target WordPress site with Sensei LMS <= 4.24.4 installed and activated.
• No authentication required.

Exploitation Steps:

1. Identify the vulnerable endpoint (e.g., /wp-json/sensei-lms/v1/sensitive-data).
2. Send a GET request without any authentication headers.
3. Observe the response containing sensitive data.

Example cURL command:

curl -X GET "http://target-site.com/wp-json/sensei-lms/v1/sensitive-data"

Expected Output:

{
  "students": [
    {"name": "John Doe", "email": "john@example.com", "progress": "75%"}
  ],
  "courses": [
    {"title": "Advanced PHP", "enrolled": 150}
  ]
}

Blue Team (Detection & Hardening)

Detection:

• Monitor for unusual access to /wp-json/sensei-lms/v1/* endpoints from unauthenticated sources.
• Look for spikes in 200 OK responses to these endpoints without prior login.

Hardening:

• Disable the plugin until a patch is available.
• Implement a Web Application Firewall (WAF) rule to block unauthenticated access to Sensei LMS REST endpoints.
• Use a plugin like "Wordfence" to add extra authorization checks.

Indicators of Compromise (IOCs)

• Network IOCs:
  • HTTP requests to /wp-json/sensei-lms/v1/sensitive-data (or similar endpoints) without authentication.
  • User-Agent strings not matching known browsers (e.g., curl/7.68.0).
• File IOCs:
  • Modified sensei-lms.php or other plugin files (check file integrity).
• Log IOCs:
  • WordPress debug log entries showing rest_api_init calls with missing permissions.

Detection Engineering

YARA Rule

rule CVE_2025_22740_Sensei_LMS_Missing_Auth {
    meta:
        description = "Detects vulnerable Sensei LMS plugin files with missing authorization"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-22740"
    strings:
        $vuln_func = "__return_true" nocase
        $sensei_path = "sensei-lms" nocase
    condition:
        $sensei_path and $vuln_func
}

Sigma Rule

title: CVE-2025-22740 - Sensei LMS Missing Authorization
id: 8a9b7c6d-5e4f-3a2b-1c0d-9e8f7a6b5c4d
status: experimental
description: Detects unauthenticated access to Sensei LMS REST API endpoints
author: Valters IT
date: 2025/04/10
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'GET'
        cs-uri-stem|startswith: '/wp-json/sensei-lms/v1/'
        sc-status: 200
    condition: selection
falsepositives:
    - Legitimate authenticated users (rare)
level: medium

Suricata Rule

alert http any any -> $HOME_NET any (
    msg:"CVE-2025-22740 - Sensei LMS Missing Authorization Attempt";
    flow:to_server,established;
    content:"GET"; http_method;
    content:"/wp-json/sensei-lms/v1/"; http_uri;
    sid:1000001;
    rev:1;
    reference:cve,2025-22740;
    classtype:attempted-recon;
    priority:2;
)

Remediation & Mitigation

Immediate Actions:

1. Disable the plugin if not critical to operations.
2. Apply virtual patching via WAF rules to block unauthenticated access to /wp-json/sensei-lms/v1/*.
3. Monitor logs for exploitation attempts.

Long-term Fix:

• Wait for an official patch from Automattic.
• Once patched, update to the latest version immediately.
• Review all WordPress plugins for similar authorization issues.

Workaround:

• Add custom code to functions.php to enforce capability checks:

add_filter('rest_pre_dispatch', function ($result, $server, $request) {
    if (strpos($request->get_route(), 'sensei-lms/v1') !== false) {
        if (!current_user_can('manage_sensei')) {
            return new WP_Error('rest_forbidden', 'Access denied', array('status' => 403));
        }
    }
    return $result;
}, 10, 3);

Valters IT
Securing Digital Frontiers