CVE-2025-31439 Overview
CVE-2025-31439 is a Cross-Site Request Forgery (CSRF) vulnerability in the Browser Caching with .htaccess WordPress plugin developed by tobias_.MerZ. The flaw affects plugin versions from 1.2.1 through the latest release at time of disclosure. It is classified under [CWE-352] (Cross-Site Request Forgery).
An attacker can trick an authenticated administrator into submitting a forged request that modifies plugin settings. Because the plugin manipulates the site's .htaccess file for browser caching directives, unauthorized changes can alter server response behavior and impact site availability or integrity.
Critical Impact
An attacker who successfully lures an authenticated WordPress administrator to a malicious page can modify browser caching configuration written to .htaccess, affecting site integrity and availability.
Affected Products
- Browser Caching with .htaccess plugin for WordPress (vendor: tobias_.MerZ)
- Affected versions: 1.2.1 through n/a (no fixed version identified in the advisory)
- WordPress sites running the plugin with administrative sessions
Discovery Timeline
- 2025-03-28 - CVE-2025-31439 published to NVD
- 2026-06-17 - Last updated in NVD database
Technical Details for CVE-2025-31439
Vulnerability Analysis
The vulnerability is a Cross-Site Request Forgery weakness in the plugin's administrative request handling. State-changing endpoints that update the plugin configuration do not adequately verify the origin or authenticity of the incoming request. WordPress provides nonce-based request validation through functions such as wp_verify_nonce() and check_admin_referer(), but these controls are either missing or improperly implemented in the affected code paths.
Exploitation requires user interaction, meaning an authenticated administrator must visit an attacker-controlled page while a valid WordPress session is active. The forged request executes with the administrator's privileges, allowing the attacker to persist configuration changes in the plugin. The confidentiality impact is none, while integrity and availability impacts are limited, reflecting the constrained scope of plugin configuration data.
Root Cause
The root cause is missing or insufficient CSRF token validation on plugin administrative actions. Without a valid nonce check tied to the user's session, the plugin accepts any well-formed POST or GET request submitted with the administrator's cookies. This maps directly to [CWE-352].
Attack Vector
The attack occurs over the network and requires user interaction. An attacker crafts an HTML page containing an auto-submitting form or image tag that targets the plugin's settings endpoint. When an authenticated administrator loads the malicious page, the browser attaches session cookies to the outbound request, and WordPress processes the action as legitimate. The attacker cannot read the response, but the write action succeeds and rewrites .htaccess caching directives.
No verified exploit code is publicly available. See the Patchstack WordPress Vulnerability advisory for additional technical context.
Detection Methods for CVE-2025-31439
Indicators of Compromise
- Unexpected modifications to the site's .htaccess file, particularly cache-control or mod_expires directives
- Plugin settings changes in the WordPress database (wp_options) without a corresponding admin audit trail
- Administrator page views immediately followed by cross-origin Referer headers pointing to unknown domains
Detection Strategies
- Monitor web server logs for POST requests to /wp-admin/ endpoints associated with the plugin that carry external or missing Referer headers
- Enable WordPress audit logging to record plugin configuration changes and correlate them with administrator activity
- Use file integrity monitoring on .htaccess to alert on unauthorized rewrites
Monitoring Recommendations
- Track administrator session activity and flag settings changes made outside normal maintenance windows
- Alert on new or modified rewrite rules in .htaccess that were not deployed through change management
- Review WordPress plugin update logs and administrative user actions on a recurring basis
How to Mitigate CVE-2025-31439
Immediate Actions Required
- Deactivate the Browser Caching with .htaccess plugin until a patched version is confirmed available
- Restrict administrator browsing sessions to trusted contexts and log out of WordPress admin when not in active use
- Audit .htaccess for unauthorized modifications and restore from a known-good backup if changes are detected
Patch Information
At the time of publication, no fixed version has been identified in the advisory. Monitor the Patchstack advisory and the plugin's WordPress.org listing for a security release.
Workarounds
- Remove the plugin and implement browser caching directives directly in the server configuration managed by an administrator
- Deploy a web application firewall rule that enforces same-origin Referer and Origin header checks on plugin admin endpoints
- Require administrators to use a dedicated browser profile for WordPress management to reduce cross-site request exposure
# Example: restrict access to the plugin admin endpoint by source IP in .htaccess
<Files "admin-post.php">
Require ip 203.0.113.10
Require ip 203.0.113.11
</Files>
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
