CVE-2025-12037: WP 404 Auto Redirect XSS Vulnerability

CVE-2025-12037 Overview

CVE-2025-12037 is a Stored Cross-Site Scripting (XSS) vulnerability affecting the WP 404 Auto Redirect to Similar Post plugin for WordPress. The vulnerability exists in all versions up to and including 1.0.5 due to insufficient input sanitization and output escaping in admin settings. This flaw allows authenticated attackers with administrator-level permissions to inject arbitrary web scripts into pages that execute whenever a user accesses an injected page.

Critical Impact

This vulnerability enables persistent script injection that can compromise administrator sessions, steal credentials, or perform unauthorized actions on multi-site WordPress installations and sites where unfiltered_html has been disabled.

Affected Products

• WP 404 Auto Redirect to Similar Post plugin versions up to and including 1.0.5
• WordPress multi-site installations
• WordPress installations where unfiltered_html capability has been disabled

Discovery Timeline

• 2026-02-18 - CVE-2025-12037 published to NVD
• 2026-02-18 - Last updated in NVD database

Technical Details for CVE-2025-12037

Vulnerability Analysis

This Stored Cross-Site Scripting vulnerability stems from improper handling of user-supplied input within the plugin's administrative settings interface. When an administrator configures the plugin settings, the input values are not properly sanitized before storage and are not adequately escaped when rendered on subsequent page loads. This creates a persistent XSS condition where malicious JavaScript payloads survive across sessions and affect all users who view the compromised pages.

The vulnerability specifically impacts WordPress environments where the unfiltered_html capability has been restricted, which is a common security hardening practice in enterprise WordPress deployments and all multi-site installations by default. In these configurations, administrators would normally be prevented from inserting raw HTML/JavaScript, but this vulnerability bypasses that protection through the plugin's flawed input handling.

Root Cause

The root cause is classified as CWE-79 (Improper Neutralization of Input During Web Page Generation). The plugin fails to implement proper input sanitization on admin settings fields before storing data to the database, and does not apply appropriate output escaping (such as esc_html(), esc_attr(), or wp_kses()) when rendering these values in the WordPress admin or frontend pages. This combination allows script content to be persisted and executed in users' browsers.

Attack Vector

The attack requires network access and is executed through the WordPress admin interface. An attacker with administrator-level credentials can navigate to the plugin's settings page and inject malicious JavaScript code into vulnerable input fields. The injected script is stored in the WordPress database and executes in the browser context of any user who subsequently views a page where the malicious content is rendered.

While the requirement for administrator privileges limits the attack surface, this vulnerability is particularly concerning in scenarios where:

• Multiple administrators manage a site and one account is compromised
• An insider threat exists within the administrative team
• The vulnerability is chained with other attacks to escalate from a lower-privileged position

The technical details of exploitation can be found in the Wordfence Vulnerability Report.

Detection Methods for CVE-2025-12037

Indicators of Compromise

• Unexpected JavaScript code or <script> tags present in the wp_options table entries related to the WP 404 Auto Redirect plugin
• Unusual admin activity logs showing repeated modifications to the plugin's settings
• Browser console errors or unexpected script execution when accessing plugin configuration pages
• Reports of session hijacking or unauthorized administrative actions

Detection Strategies

• Review WordPress database for stored XSS payloads in plugin option values by querying the wp_options table for entries containing <script>, javascript:, or event handlers like onerror
• Implement Content Security Policy (CSP) headers to detect and block inline script execution, which will generate violation reports if XSS payloads attempt to execute
• Deploy web application firewall (WAF) rules to monitor and alert on suspicious patterns in admin POST requests to plugin settings endpoints
• Enable and review WordPress audit logging for changes to plugin configurations

Monitoring Recommendations

• Configure SentinelOne Singularity XDR to monitor for suspicious JavaScript execution patterns and DOM manipulation indicative of XSS attacks
• Implement file integrity monitoring on WordPress core files and plugin directories to detect unauthorized modifications
• Set up alerts for administrative actions performed during unusual hours or from unexpected IP addresses
• Monitor outbound network connections from web servers for data exfiltration attempts

How to Mitigate CVE-2025-12037

Immediate Actions Required

• Update the WP 404 Auto Redirect to Similar Post plugin to a patched version if available, or deactivate and remove the plugin until a fix is released
• Audit current plugin settings for any evidence of injected malicious scripts
• Review WordPress admin user accounts and revoke access for any suspicious or unnecessary administrator accounts
• Implement strict Content Security Policy headers to mitigate the impact of stored XSS payloads

Patch Information

Plugin update information and changelogs are available through the WordPress Plugin Changelog. Site administrators should monitor for version updates beyond 1.0.5 that address this vulnerability. Review the Wordfence Vulnerability Report for the latest remediation guidance.

Workarounds

• Disable or uninstall the WP 404 Auto Redirect to Similar Post plugin until a patched version is available
• Limit administrator account access using the principle of least privilege and consider implementing role-based access controls
• Deploy a Web Application Firewall (WAF) with rules to detect and block XSS payloads in HTTP requests
• Enable unfiltered_html restrictions if not already applied and ensure multi-site network configurations are properly hardened

# WordPress CLI commands to audit and manage the vulnerable plugin
# Check current plugin version
wp plugin list --name=wp-404-auto-redirect-to-similar-post --format=table

# Deactivate the vulnerable plugin as a temporary mitigation
wp plugin deactivate wp-404-auto-redirect-to-similar-post

# Check for plugin updates
wp plugin update wp-404-auto-redirect-to-similar-post --dry-run

# Review plugin options for suspicious content
wp option get wp_404_auto_redirect_options --format=json