CVE-2026-3529: Drupal Google Analytics GA4 XSS Vulnerability

CVE-2026-3529 Overview

CVE-2026-3529 is a Cross-Site Scripting (XSS) vulnerability affecting the Drupal Google Analytics GA4 contributed module. The vulnerability stems from improper neutralization of input during web page generation, allowing attackers to inject malicious scripts into web pages viewed by other users. This XSS flaw affects all versions of the Google Analytics GA4 module from 0.0.0 before 1.1.14.

Critical Impact
Successful exploitation could allow attackers to execute arbitrary JavaScript in the context of authenticated user sessions, potentially leading to session hijacking, credential theft, defacement, or further attacks against site administrators.

Affected Products

Drupal Google Analytics GA4 module versions 0.0.0 through 1.1.13
Drupal-based websites utilizing the vulnerable Google Analytics GA4 module
Sites that have not upgraded to version 1.1.14 or later

Discovery Timeline

2026-03-26 - CVE-2026-3529 published to NVD
2026-03-26 - Last updated in NVD database

Technical Details for CVE-2026-3529

Vulnerability Analysis

This vulnerability is classified under CWE-79 (Improper Neutralization of Input During Web Page Generation), commonly known as Cross-Site Scripting. The Google Analytics GA4 module for Drupal fails to properly sanitize or encode user-supplied input before rendering it in web pages. This allows an attacker to craft malicious input containing JavaScript code that will be executed in the browser of any user who views the affected content.

XSS vulnerabilities in Drupal modules can be particularly dangerous when they affect administrative interfaces or content that is viewed by authenticated users with elevated privileges. Attackers can leverage these flaws to steal session cookies, perform actions on behalf of the victim, or escalate their access within the Drupal installation.

Root Cause

The root cause of this vulnerability lies in insufficient input validation and output encoding within the Google Analytics GA4 module. User-controlled data is incorporated into the HTML output without proper sanitization, allowing script tags or JavaScript event handlers to be injected and executed by the victim's browser. Drupal provides robust APIs for sanitizing output, but the vulnerable module code failed to utilize these protections appropriately.

Attack Vector

An attacker can exploit this vulnerability by submitting specially crafted input containing malicious JavaScript code through the affected module's functionality. When an unsuspecting user—particularly a site administrator—views the page containing the malicious payload, the injected script executes within their browser context. This could enable the attacker to:

Steal session tokens and authentication cookies
Perform unauthorized actions using the victim's credentials
Redirect users to malicious websites
Modify page content to conduct phishing attacks
Access sensitive information displayed on the page

For detailed technical information, refer to the Drupal Security Advisory.

Detection Methods for CVE-2026-3529

Indicators of Compromise

Unexpected JavaScript code appearing in page source or database entries associated with Google Analytics configuration
Reports from users of suspicious pop-ups, redirects, or unusual behavior on pages utilizing the GA4 module
Web application firewall (WAF) logs showing blocked XSS payloads targeting Drupal endpoints
Anomalous session activity or authentication events following user visits to affected pages

Detection Strategies

Review Drupal watchdog logs for suspicious input patterns containing script tags or JavaScript event handlers
Deploy Content Security Policy (CSP) headers and monitor for policy violation reports that may indicate XSS attempts
Utilize web application firewalls with XSS detection rules to identify and block exploitation attempts
Conduct regular security audits of contributed module configurations and stored data

Monitoring Recommendations

Enable detailed logging for the Google Analytics GA4 module configuration changes
Monitor HTTP response bodies for unexpected inline scripts or event handlers
Set up alerting for CSP violation reports that may indicate active exploitation
Track module versions across Drupal installations to identify unpatched instances

How to Mitigate CVE-2026-3529

Immediate Actions Required

Update the Google Analytics GA4 module to version 1.1.14 or later immediately
Review existing module configuration data for any injected malicious content
Implement Content Security Policy headers to reduce the impact of any undetected XSS payloads
Invalidate and regenerate session tokens for all administrative users as a precautionary measure

Patch Information

The Drupal security team has addressed this vulnerability in Google Analytics GA4 module version 1.1.14. Site administrators should update the module through standard Drupal update procedures. For complete patch details and upgrade instructions, consult the Drupal Security Advisory.

Workarounds

If immediate patching is not possible, consider temporarily disabling the Google Analytics GA4 module until the update can be applied
Implement strict Content Security Policy headers to mitigate the impact of XSS attacks
Restrict access to module configuration pages to only essential administrative users
Deploy a web application firewall with XSS filtering rules as an additional layer of defense

bash

# Drupal module update via Composer
composer update drupal/google_analytics_ga4

# Clear Drupal caches after update
drush cache:rebuild

# Verify installed module version
drush pm:list --filter=google_analytics_ga4