CVE-2026-0749: Drupal Form Builder XSS Vulnerability

CVE-2026-0749 Overview

CVE-2026-0749 is a Cross-Site Scripting (XSS) vulnerability affecting the Drupal Form Builder module. The vulnerability stems from improper neutralization of user-supplied input during web page generation, allowing attackers to inject malicious scripts into web pages viewed by other users. This issue specifically impacts Drupal Form Builder versions 7.X-1.0 through 7.X-1.22.

Critical Impact

Authenticated attackers can exploit this XSS vulnerability to execute arbitrary JavaScript in the context of other users' browsers, potentially leading to session hijacking, credential theft, or defacement of affected Drupal sites.

Affected Products

• Drupal Form Builder 7.X-1.0 through 7.X-1.22

Discovery Timeline

• 2026-01-28 - CVE-2026-0749 published to NVD
• 2026-01-29 - Last updated in NVD database

Technical Details for CVE-2026-0749

Vulnerability Analysis

This Cross-Site Scripting vulnerability exists due to insufficient input validation and output encoding within the Drupal Form Builder module. When processing user-supplied data, the module fails to properly sanitize input before rendering it in web pages, creating an opportunity for script injection.

The vulnerability requires an authenticated user with low privileges to exploit, and victim interaction is necessary for successful exploitation. An attacker can craft malicious input containing JavaScript code that will be stored or reflected back to other users viewing the affected pages. When the victim's browser processes this content, the malicious script executes in the security context of the vulnerable Drupal site.

The impact is primarily limited to integrity violations in both the vulnerable system and potentially connected systems. While confidentiality is not directly compromised, the ability to execute arbitrary scripts can lead to secondary attacks such as credential harvesting or session token theft.

Root Cause

The root cause of CVE-2026-0749 is classified as CWE-79 (Improper Neutralization of Input During Web Page Generation). The Drupal Form Builder module does not adequately sanitize user-controllable input fields before incorporating them into dynamically generated web pages. This allows HTML and JavaScript content to be injected and rendered without proper encoding or escaping.

Attack Vector

The attack vector is network-based, requiring an authenticated attacker to submit crafted input containing malicious script content through the Form Builder interface. The attack complexity is low, though it requires victim interaction—another user must view the page containing the injected content for the malicious script to execute.

The exploitation scenario involves an authenticated attacker injecting XSS payloads into form fields or configurations that are later rendered to other users. When victims access pages containing the malicious content, the script executes in their browser context, potentially allowing the attacker to steal session cookies, perform actions on behalf of the victim, or redirect users to malicious sites.

For technical implementation details regarding this vulnerability, refer to the Tag1 Security Advisory.

Detection Methods for CVE-2026-0749

Indicators of Compromise

• Unusual JavaScript or HTML tags appearing in Form Builder database fields or configurations
• Unexpected script execution events in browser developer console logs when accessing Form Builder pages
• User reports of unexpected redirects or pop-ups when interacting with forms

Detection Strategies

• Implement Web Application Firewall (WAF) rules to detect XSS payloads in requests to Form Builder endpoints
• Deploy Content Security Policy (CSP) headers to detect and block inline script execution
• Monitor Drupal watchdog logs for suspicious form submissions containing script tags or JavaScript event handlers
• Utilize SentinelOne's behavioral AI to detect anomalous browser activities indicative of XSS exploitation

Monitoring Recommendations

• Enable detailed logging for the Form Builder module to capture all form submissions and configuration changes
• Configure alerts for CSP violation reports indicating attempted script injection
• Monitor for unusual patterns in user session activity that may indicate session hijacking post-exploitation

How to Mitigate CVE-2026-0749

Immediate Actions Required

• Update Drupal Form Builder to a patched version beyond 7.X-1.22 if available from the vendor
• Review and audit existing Form Builder configurations and stored data for injected malicious content
• Implement Content Security Policy headers to restrict inline script execution
• Enable input validation and output encoding at the application level where possible

Patch Information

Administrators should consult the official security advisories for patch availability. Review the Tag1 Security Advisory and HeroDev CVE-2026-0749 listing for the latest remediation guidance and patch information.

Workarounds

• Implement strict Content Security Policy headers to mitigate the impact of potential XSS attacks
• Restrict Form Builder module access to only trusted administrative users until patching is complete
• Deploy a Web Application Firewall with XSS detection rules to filter malicious input
• Consider temporarily disabling the Form Builder module if it is not essential to site operations

# Example: Add Content Security Policy header in Apache configuration
# Add to .htaccess or Apache virtual host configuration
Header set Content-Security-Policy "default-src 'self'; script-src 'self'; style-src 'self' 'unsafe-inline';"