CVE-2025-13694: AA Block Country Auth Bypass Vulnerability

CVE-2025-13694 Overview

The AA Block Country plugin for WordPress contains an IP Address Spoofing vulnerability in versions up to and including 1.0.1. This security flaw exists because the plugin improperly trusts user-supplied HTTP headers, specifically HTTP_X_FORWARDED_FOR, to determine the client's IP address without proper validation or verification that the server is behind a trusted proxy. This weakness allows unauthenticated attackers to bypass IP-based geographical access restrictions by spoofing their IP address via the X-Forwarded-For header.

Critical Impact

Attackers can bypass geographical IP-based access controls, potentially gaining access to restricted content or functionality intended for specific regions or blocked to certain geographic locations.

Affected Products

• AA Block Country plugin for WordPress version 1.0.1 and earlier
• WordPress installations using the AA Block Country plugin for geo-blocking functionality
• Web applications relying on AA Block Country for IP-based access control

Discovery Timeline

• 2026-01-07 - CVE-2025-13694 published to NVD
• 2026-01-08 - Last updated in NVD database

Technical Details for CVE-2025-13694

Vulnerability Analysis

This vulnerability is classified as CWE-348 (Use of Less Trusted Source). The AA Block Country plugin is designed to restrict access to WordPress sites based on the visitor's geographical location, determined by their IP address. However, the plugin's implementation contains a critical flaw in how it obtains the client's IP address.

Rather than relying solely on the REMOTE_ADDR server variable, which contains the actual connecting IP address, the plugin prioritizes user-controllable HTTP headers like X-Forwarded-For. While this header is legitimately used by proxies and load balancers to preserve the original client IP, the plugin fails to verify whether the request actually originated from a trusted proxy.

This design flaw means an attacker can simply set the X-Forwarded-For header to any IP address they choose. By spoofing an IP address from an allowed geographic region, attackers can completely bypass the country-blocking functionality the plugin is meant to provide.

Root Cause

The root cause of this vulnerability lies in the plugin's IP address resolution logic located in aablockcountry.php. The code trusts the HTTP_X_FORWARDED_FOR header without validating:

1. Whether the request originated from a known, trusted proxy server
2. Whether the proxy chain is legitimate and properly configured
3. The integrity of the header value itself

This is a common security anti-pattern in web applications that implement IP-based access controls, particularly when deployed behind reverse proxies or CDNs. The proper approach requires explicitly configuring trusted proxy addresses and only accepting forwarded headers from those sources.

Attack Vector

The attack vector is network-based and requires no authentication or user interaction. An attacker can exploit this vulnerability by:

1. Identifying that a WordPress site uses the AA Block Country plugin for geo-blocking
2. Crafting an HTTP request with a manipulated X-Forwarded-For header containing an IP address from an allowed country
3. Sending the request directly to the target WordPress site
4. Bypassing all geographic restrictions implemented by the plugin

The attack is trivial to execute using common HTTP tools like curl, browser developer tools, or intercepting proxies. For example, an attacker blocked by IP geolocation could include a header with a US-based IP address to gain access to a site that blocks non-US visitors.

Detection Methods for CVE-2025-13694

Indicators of Compromise

• Unusual patterns of X-Forwarded-For headers in access logs, especially when the header value does not match expected proxy infrastructure
• Access from geographic regions that should be blocked, visible in analytics or access logs
• Multiple requests with different X-Forwarded-For values originating from the same actual source IP
• Inconsistencies between GeoIP lookup results and actual request origins

Detection Strategies

• Review web server access logs for requests containing suspicious X-Forwarded-For headers that don't originate from legitimate proxy infrastructure
• Implement log correlation to detect discrepancies between the connecting IP (REMOTE_ADDR) and forwarded headers
• Monitor for unusual access patterns from IPs claiming to be from diverse geographic locations but sharing behavioral fingerprints
• Deploy Web Application Firewall (WAF) rules to flag or block requests with X-Forwarded-For headers from untrusted sources

Monitoring Recommendations

• Enable verbose logging on WordPress and the web server to capture all HTTP headers for security analysis
• Implement real-time alerting for access attempts that bypass geographic restrictions
• Periodically audit access logs to identify patterns consistent with IP spoofing attacks
• Consider implementing secondary geographic verification mechanisms for sensitive operations

How to Mitigate CVE-2025-13694

Immediate Actions Required

• Review whether your WordPress installation uses the AA Block Country plugin version 1.0.1 or earlier
• If using the vulnerable plugin, evaluate alternative geo-blocking solutions or implement server-level IP restrictions
• Configure your web server or reverse proxy to properly sanitize or remove client-supplied X-Forwarded-For headers before they reach WordPress
• Implement additional access controls that do not rely solely on IP-based geographic blocking

Patch Information

As of the last NVD update on 2026-01-08, check the WordPress Plugin Source Code for any updates that address this vulnerability. Review the Wordfence Vulnerability Analysis for the latest mitigation guidance and patch status.

Workarounds

• Configure the web server (Apache, Nginx) to strip or override X-Forwarded-For headers unless they originate from trusted proxy IP addresses
• Implement geo-blocking at the web server or firewall level using REMOTE_ADDR rather than relying on application-level plugins
• Deploy a Web Application Firewall (WAF) that can properly handle and validate forwarded headers
• Consider using SentinelOne Singularity for comprehensive endpoint and cloud workload protection that can detect and respond to suspicious access patterns

# Nginx configuration to only trust X-Forwarded-For from known proxies
# Add to nginx.conf or server block
set_real_ip_from 10.0.0.0/8;      # Trusted proxy network
set_real_ip_from 172.16.0.0/12;   # Trusted proxy network
real_ip_header X-Forwarded-For;
real_ip_recursive on;