CVE-2025-26562: RSS Filter CSRF Vulnerability

CVE-2025-26562 Overview

CVE-2025-26562 is a Cross-Site Request Forgery (CSRF) vulnerability in the RSS Filter WordPress plugin developed by Shambhu Patnaik. This vulnerability can be chained with a Stored Cross-Site Scripting (XSS) attack, allowing malicious actors to inject persistent scripts into the WordPress site through forged requests. When an authenticated administrator visits a malicious page while logged into the WordPress admin panel, the attacker can execute arbitrary actions on their behalf, including injecting malicious JavaScript that persists in the database.

Critical Impact

Attackers can leverage this CSRF-to-Stored-XSS vulnerability chain to inject persistent malicious scripts, potentially leading to session hijacking, administrative account compromise, malware distribution to site visitors, and complete site takeover.

Affected Products

• RSS Filter WordPress Plugin version 1.2 and earlier
• All installations of the rss-filter plugin up to and including version 1.2

Discovery Timeline

• 2025-02-13 - CVE-2025-26562 published to NVD
• 2026-04-15 - Last updated in NVD database

Technical Details for CVE-2025-26562

Vulnerability Analysis

This vulnerability represents a dangerous attack chain combining Cross-Site Request Forgery (CSRF) with Stored Cross-Site Scripting (XSS). The RSS Filter plugin fails to implement proper CSRF token validation on its administrative functions, allowing attackers to craft malicious requests that execute in the context of an authenticated administrator's session.

The lack of nonce verification on form submissions means that when an administrator visits an attacker-controlled page or clicks a malicious link, the attacker can submit arbitrary data to the plugin's settings. Because the plugin also lacks proper output encoding and input sanitization, this injected data is stored in the database and rendered without escaping, resulting in Stored XSS.

This vulnerability is classified under CWE-352 (Cross-Site Request Forgery), which occurs when a web application does not sufficiently verify whether a well-formed, valid, consistent request was intentionally provided by the user who submitted the request.

Root Cause

The root cause of this vulnerability is twofold:

1. Missing CSRF Protection: The RSS Filter plugin does not implement WordPress nonce verification on administrative form handlers. WordPress provides built-in functions like wp_nonce_field() and wp_verify_nonce() that should be used to validate that form submissions originate from legitimate user actions within the WordPress admin interface.

2. Insufficient Input Sanitization: User-supplied input is stored without proper sanitization using functions like sanitize_text_field() or wp_kses(), and subsequently rendered without escaping using esc_html() or esc_attr(), enabling the XSS payload to execute.

Attack Vector

The attack requires social engineering to lure an authenticated WordPress administrator to visit a malicious webpage or click a crafted link. The attack flow proceeds as follows:

1. The attacker crafts a malicious HTML page containing a hidden form that targets the vulnerable RSS Filter plugin endpoint
2. The form includes XSS payload in the input fields that will be stored by the plugin
3. When an authenticated administrator visits the attacker's page, the form auto-submits via JavaScript
4. The malicious data is saved to the WordPress database through the plugin's unprotected handler
5. When any user (including administrators) subsequently views pages where the RSS Filter output is displayed, the stored XSS payload executes in their browser context

The vulnerability does not require authentication from the attacker's perspective—only that the victim be authenticated as an administrator when triggering the CSRF request.

Detection Methods for CVE-2025-26562

Indicators of Compromise

• Unexpected or suspicious JavaScript code within RSS Filter plugin settings or database entries
• Unusual outbound requests from the WordPress site to unknown external domains
• Modified plugin configuration entries that were not changed by administrators
• Browser security warnings or blocked scripts when viewing pages with RSS feed content

Detection Strategies

• Review WordPress database tables for unexpected script tags or JavaScript event handlers in RSS Filter related options
• Monitor web server access logs for suspicious POST requests to RSS Filter plugin endpoints from external referrers
• Implement Content Security Policy (CSP) headers to detect and block inline script execution attempts
• Use WordPress security plugins that monitor for unauthorized settings changes

Monitoring Recommendations

• Enable WordPress audit logging to track all plugin settings modifications with timestamps and user context
• Configure web application firewall (WAF) rules to detect CSRF attack patterns and XSS payloads
• Regularly scan stored content and plugin settings for malicious script injections
• Monitor browser console errors that may indicate blocked XSS attempts

How to Mitigate CVE-2025-26562

Immediate Actions Required

• Deactivate and remove the RSS Filter plugin (rss-filter) from all WordPress installations immediately
• Audit WordPress database for any stored XSS payloads that may have been injected through this vulnerability
• Review administrator user sessions and force password resets if compromise is suspected
• Check for any unauthorized administrator accounts or modified user privileges

Patch Information

As of the available data, no patched version has been released for the RSS Filter plugin. The vulnerability affects all versions from the initial release through version 1.2. Site administrators should consider this plugin abandoned or vulnerable and seek alternative solutions for RSS filtering functionality.

For detailed vulnerability information, refer to the Patchstack WordPress Vulnerability Report.

Workarounds

• Remove the RSS Filter plugin entirely and replace with a maintained alternative that implements proper CSRF protection
• If removal is not immediately possible, restrict access to the WordPress admin panel to trusted IP addresses only
• Implement a Web Application Firewall (WAF) with rules to block CSRF attacks and XSS payloads
• Add Content Security Policy headers to mitigate the impact of any successful XSS injection

# WordPress CLI command to deactivate the vulnerable plugin
wp plugin deactivate rss-filter --path=/var/www/html/wordpress

# Search for potential XSS payloads in WordPress options table
wp db query "SELECT option_name, option_value FROM wp_options WHERE option_value LIKE '%<script%' OR option_value LIKE '%javascript:%'" --path=/var/www/html/wordpress

# Force logout all users to invalidate potentially compromised sessions
wp user session destroy --all --path=/var/www/html/wordpress