CVE-2025-23537: Google Tag Manager Plugin CSRF Vulnerability

CVE-2025-23537 Overview

CVE-2025-23537 is a Cross-Site Request Forgery (CSRF) vulnerability in the WordPress "Add Custom Google Tag Manager" plugin that allows attackers to inject malicious scripts through Stored Cross-Site Scripting (XSS). The vulnerability exists due to missing or improper CSRF token validation, enabling attackers to trick authenticated administrators into executing unintended actions that result in persistent XSS payloads being stored in the WordPress database.

Critical Impact

Attackers can chain CSRF with Stored XSS to inject persistent malicious scripts into WordPress sites, potentially leading to admin account takeover, data theft, and site defacement.

Affected Products

• Add Custom Google Tag Manager WordPress Plugin version 1.0.3 and earlier
• WordPress installations using the affected plugin versions

Discovery Timeline

• 2025-01-16 - CVE-2025-23537 published to NVD
• 2026-04-15 - Last updated in NVD database

Technical Details for CVE-2025-23537

Vulnerability Analysis

This vulnerability combines two common web application weaknesses: Cross-Site Request Forgery (CSRF) and Stored Cross-Site Scripting (XSS). The plugin fails to implement proper CSRF protection on its settings pages, allowing attackers to craft malicious requests that, when executed by an authenticated administrator, inject JavaScript code into plugin configuration fields. Since the injected content is stored in the database and rendered without proper output encoding, the malicious scripts execute whenever the affected pages are loaded.

The attack requires social engineering to trick an administrator into visiting a malicious page or clicking a crafted link while authenticated to the WordPress site. Once successful, the stored XSS payload persists and can affect all users who access the compromised pages, including other administrators.

Root Cause

The root cause is twofold: the plugin's settings forms do not include or validate CSRF tokens (nonces in WordPress terminology), and user-supplied input is stored and subsequently displayed without proper sanitization or output escaping. WordPress provides built-in functions like wp_nonce_field() and wp_verify_nonce() for CSRF protection, as well as esc_html() and esc_attr() for output escaping, but these security measures were not properly implemented in the affected plugin versions.

Attack Vector

The attack follows a classic CSRF-to-Stored-XSS chain. An attacker creates a malicious webpage containing a hidden form that targets the vulnerable plugin's settings endpoint. When an authenticated WordPress administrator visits this page, the form automatically submits, updating the plugin settings with attacker-controlled JavaScript code. This code is then stored in the database and executes in the context of any user's browser session when viewing pages that include the Google Tag Manager output.

Since no verified code examples are available for this vulnerability, security researchers and administrators should refer to the Patchstack WordPress Vulnerability Report for detailed technical information about the vulnerability mechanism and exploitation vectors.

Detection Methods for CVE-2025-23537

Indicators of Compromise

• Unexpected or suspicious JavaScript code in the Google Tag Manager plugin configuration fields
• Unusual administrator activity logs showing settings changes without corresponding legitimate user actions
• Reports of browser warnings or unexpected script execution from site visitors
• Unauthorized modifications to plugin settings or unexpected outbound network connections from the WordPress admin interface

Detection Strategies

• Audit plugin configuration settings for any unauthorized or malicious JavaScript code injection
• Review WordPress admin access logs for suspicious activity patterns, particularly settings changes from unusual IP addresses or at unexpected times
• Implement Content Security Policy (CSP) headers to detect and block unauthorized inline script execution
• Use web application firewall (WAF) rules to monitor and alert on suspicious form submissions to the plugin's settings endpoints

Monitoring Recommendations

• Enable and regularly review WordPress audit logging for all plugin configuration changes
• Monitor for referrer anomalies in requests to plugin settings pages that could indicate CSRF attacks
• Implement browser-based XSS detection mechanisms to identify stored XSS payloads
• Set up alerting for any modifications to the Google Tag Manager plugin settings outside of normal administrative workflows

How to Mitigate CVE-2025-23537

Immediate Actions Required

• Remove or deactivate the Add Custom Google Tag Manager plugin if version 1.0.3 or earlier is installed
• Review current plugin settings for any signs of injected malicious code and remove any unauthorized content
• Audit administrator accounts for signs of compromise and rotate credentials if necessary
• Consider using alternative Google Tag Manager integration methods or plugins with better security practices

Patch Information

As of the last CVE update, users should check the WordPress plugin repository for updated versions of the Add Custom Google Tag Manager plugin that address this vulnerability. If no patched version is available, consider migrating to a well-maintained alternative plugin for Google Tag Manager integration. Refer to the Patchstack vulnerability report for the latest remediation guidance.

Workarounds

• Deactivate and remove the vulnerable plugin until a security patch is available
• Implement additional authentication requirements for accessing plugin settings pages
• Use a Web Application Firewall (WAF) to filter malicious requests targeting WordPress plugin endpoints
• Restrict administrator access to trusted IP addresses to reduce the attack surface for CSRF attacks

# WordPress CLI command to deactivate the vulnerable plugin
wp plugin deactivate add-custom-google-tag-manager --path=/var/www/html

# Check for any suspicious content in WordPress options related to the plugin
wp option get add_custom_gtm_options --path=/var/www/html

# Enable WordPress debug logging to monitor for suspicious activity
# Add to wp-config.php:
# define('WP_DEBUG', true);
# define('WP_DEBUG_LOG', true);