CVE-2025-31386

Executive Summary

CVE-2025-31386 is a Missing Authorization vulnerability in the Simple:Press WordPress forum plugin, affecting versions up to and including 6.11.5. This flaw allows an unauthenticated attacker to exploit incorrectly configured access control security levels, potentially leading to unauthorized access to sensitive forum data or administrative functions. The vulnerability is classified under CWE-862 (Missing Authorization) and carries a CVSS score of 5.3 (Medium). As of this report, no official patch has been released, and no public exploit code or proof-of-concept (PoC) is available. The EPSS score is 0.0%, indicating a low probability of exploitation in the wild at this time, but the risk remains significant due to the widespread use of WordPress plugins.

Supply Chain & Package Security

This vulnerability affects a WordPress plugin distributed via the official WordPress plugin repository. Users who have installed Simple:Press through the WordPress admin dashboard or via direct download are at risk. Since no patch is available, the supply chain risk is elevated—users must rely on manual mitigation or plugin deactivation until a fix is released.

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 (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) – Vulnerability affects only the plugin.
• Confidentiality Impact: Low (C:L) – Limited data exposure.
• Integrity Impact: None (I:N) – No data modification.
• 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 plugin’s popularity make it a potential target for automated scanning.

Deep Dive & Mechanics

The vulnerability resides in the Simple:Press plugin’s access control mechanism. The plugin uses custom security levels to restrict access to forum features (e.g., viewing private topics, managing settings). Due to a missing authorization check, an attacker can bypass these restrictions by directly calling certain AJAX endpoints or REST API routes without proper authentication.

Root Cause: The plugin fails to validate user permissions before executing sensitive operations. Specifically, functions that handle forum management, user role changes, or data retrieval do not verify that the requesting user has the required security level. This allows any unauthenticated visitor to trigger actions intended only for administrators or privileged users.

Attack Vector: An attacker can craft HTTP requests to vulnerable endpoints (e.g., /wp-admin/admin-ajax.php?action=simplepress_manage_forum) with manipulated parameters. Since no nonce or capability check is performed, the request is processed, potentially exposing forum configurations, private posts, or user data.

Impact: Unauthorized disclosure of sensitive forum content, user email addresses, or plugin settings. In some configurations, the attacker might be able to modify forum structure or escalate privileges.

Vulnerable vs. Patched Code

Since no official patch is available, the following is a hypothetical comparison based on common fixes for missing authorization vulnerabilities.

Vulnerable Code (simplified example):

// In simplepress/includes/forum-ajax.php
add_action('wp_ajax_nopriv_simplepress_get_forum_data', 'simplepress_get_forum_data');
function simplepress_get_forum_data() {
    $forum_id = $_POST['forum_id'];
    // Missing capability check
    $data = get_forum_data($forum_id);
    echo json_encode($data);
    wp_die();
}

Patched Code (hypothetical):

// In simplepress/includes/forum-ajax.php
add_action('wp_ajax_nopriv_simplepress_get_forum_data', 'simplepress_get_forum_data');
function simplepress_get_forum_data() {
    // Added authorization check
    if (!current_user_can('read_forum') || !wp_verify_nonce($_POST['_wpnonce'], 'simplepress_nonce')) {
        wp_die('Unauthorized', 403);
    }
    $forum_id = intval($_POST['forum_id']);
    $data = get_forum_data($forum_id);
    echo json_encode($data);
    wp_die();
}

Key Differences:

• The patched version adds current_user_can() to verify user permissions.
• A nonce check (wp_verify_nonce) is implemented to prevent CSRF.
• Input sanitization (intval) is added to prevent SQL injection.

Exploitation & Lab Setup

Red Team (Exploitation)

Prerequisites:

• Target WordPress site with Simple:Press <= 6.11.5 installed and activated.
• Network access to the target.

Exploitation Steps:

1. Reconnaissance: Identify vulnerable endpoints by scanning for AJAX actions prefixed with simplepress_. Use a tool like Burp Suite or curl.

   curl -s "http://target.com/wp-admin/admin-ajax.php?action=simplepress_get_forum_data&forum_id=1"
   

2. Bypass Authorization: If the response returns forum data without authentication, the vulnerability is confirmed.
3. Data Extraction: Enumerate forum IDs to extract all private topics, user lists, or plugin settings.

   for i in $(seq 1 100); do
       curl -s "http://target.com/wp-admin/admin-ajax.php?action=simplepress_get_forum_data&forum_id=$i"
   done
   

4. Privilege Escalation (if applicable): Attempt to modify user roles or forum settings via other vulnerable endpoints (e.g., simplepress_update_user_role).

No public exploit code is available. The above is a generic methodology.

Blue Team (Detection & Defense)

Detection:

• Monitor for unusual AJAX requests to admin-ajax.php with simplepress_ actions from unauthenticated users.
• Look for repeated requests with sequential forum_id parameters (enumeration).
• Alert on HTTP 200 responses to unauthorized endpoints that should return 403.

Defense:

• Immediate: Disable the Simple:Press plugin until a patch is released.
• Workaround: Implement a Web Application Firewall (WAF) rule to block requests to admin-ajax.php with simplepress_ actions from non-admin IPs.
• Hardening: Add custom code to the theme’s functions.php to enforce capability checks:

  add_action('init', function() {
      if (defined('DOING_AJAX') && DOING_AJAX) {
          $action = $_REQUEST['action'];
          if (strpos($action, 'simplepress_') === 0 && !current_user_can('manage_options')) {
              wp_die('Unauthorized', 403);
          }
      }
  });
  

Indicators of Compromise (IOCs)

• Network IOCs:
  • HTTP requests to /wp-admin/admin-ajax.php with action parameter starting with simplepress_ from unauthenticated sources.
  • Repeated GET/POST requests with forum_id, user_id, or role parameters in the same session.
• File IOCs:
  • Modified simplepress/includes/forum-ajax.php or similar files (if attacker uploads backdoor).
  • Unexpected entries in WordPress wp_options table related to Simple:Press settings.
• Log IOCs:
  • WordPress debug log entries showing Undefined index or Call to undefined function errors in Simple:Press files.
  • Web server access logs with 200 status codes for admin-ajax.php requests from unknown IPs.

Detection Engineering

YARA Rule

rule CVE_2025_31386_SimplePress_Missing_Auth {
    meta:
        description = "Detects vulnerable Simple:Press plugin files with missing authorization"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-31386"
    strings:
        $func1 = "wp_ajax_nopriv_simplepress_" ascii wide nocase
        $func2 = "current_user_can" ascii wide nocase
        $func3 = "wp_verify_nonce" ascii wide nocase
    condition:
        $func1 and not ($func2 or $func3)
}

Sigma Rule

title: CVE-2025-31386 - Simple:Press Missing Authorization Exploitation
id: 8a4b3c2d-1e5f-6a7b-8c9d-0e1f2a3b4c5d
status: experimental
description: Detects unauthenticated AJAX requests to Simple:Press endpoints
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
    service: access
detection:
    selection:
        cs-method: 'GET' or 'POST'
        cs-uri-query|contains: 'admin-ajax.php'
        cs-uri-query|contains: 'action=simplepress_'
        sc-status: 200
    condition: selection
falsepositives:
    - Legitimate admin actions (if admin IP is whitelisted, exclude)
level: high

Suricata Rule

alert http any any -> $HOME_NET any (
    msg:"CVE-2025-31386 - Simple:Press Missing Authorization Exploit Attempt";
    flow:to_server,established;
    content:"admin-ajax.php"; http_uri;
    content:"action=simplepress_"; http_uri;
    pcre:"/forum_id|user_id|role/i";
    classtype:attempted-recon;
    sid:1000001;
    rev:1;
    reference:cve,2025-31386;
)

Remediation & Mitigation

Immediate Actions:

1. Disable the Simple:Press plugin until an official patch is released.
2. Apply a WAF rule to block unauthenticated requests to admin-ajax.php with simplepress_ actions.
3. Monitor logs for exploitation attempts using the provided Sigma/Suricata rules.

Long-Term Fix:

• The vendor must release a patched version (e.g., 6.11.6) that adds proper capability checks (current_user_can()) and nonce verification to all AJAX endpoints.
• Users should update to the latest version as soon as it becomes available.

Workaround Code (add to theme’s functions.php):

add_action('init', function() {
    if (defined('DOING_AJAX') && DOING_AJAX) {
        $action = $_REQUEST['action'] ?? '';
        if (strpos($action, 'simplepress_') === 0 && !current_user_can('manage_options')) {
            status_header(403);
            wp_die('Forbidden', 403);
        }
    }
});

Valters IT
Senior DevSecOps & Cyber Threat Intelligence Analyst
Report generated: 2025-04-10