CVE-2025-13984: Drupal Next.js XSS Vulnerability

CVE-2025-13984 Overview

A Permissive Cross-domain Security Policy with Untrusted Domains vulnerability has been identified in the Drupal Next.js module. This security flaw enables Cross-Site Scripting (XSS) attacks due to improper handling of cross-domain security policies, potentially allowing attackers to execute malicious scripts in the context of affected web applications.

Critical Impact

This vulnerability allows attackers to exploit permissive cross-domain policies to execute XSS attacks, potentially compromising user sessions, stealing sensitive data, or performing unauthorized actions on behalf of authenticated users.

Affected Products

• Drupal Next.js module versions from 0.0.0 before 1.6.4
• Drupal Next.js module versions from 2.0.0 before 2.0.1

Discovery Timeline

• 2026-01-28 - CVE CVE-2025-13984 published to NVD
• 2026-01-29 - Last updated in NVD database

Technical Details for CVE-2025-13984

Vulnerability Analysis

This vulnerability is classified under CWE-942 (Permissive Cross-domain Policy with Untrusted Domains). The Drupal Next.js module fails to properly restrict cross-domain interactions, allowing untrusted domains to be included in the security policy. This permissive configuration creates a pathway for Cross-Site Scripting attacks, where malicious scripts from untrusted sources can execute within the context of the vulnerable application.

The attack requires user interaction as the victim must visit a malicious page or click a crafted link. Once triggered, the attack can potentially impact resources beyond the vulnerable component due to the changed scope characteristic of this vulnerability. While the vulnerability does not directly compromise system availability, it enables unauthorized access to sensitive information and allows modification of displayed content.

Root Cause

The root cause lies in the overly permissive cross-domain security policy implementation within the Drupal Next.js module. The module does not adequately validate or restrict which domains are trusted when enforcing cross-origin resource sharing (CORS) or similar security policies. This allows malicious actors to exploit the trust relationship and inject scripts that execute in the user's browser session.

Attack Vector

The attack is network-based and can be executed remotely without requiring authentication. An attacker crafts a malicious request or page that exploits the permissive cross-domain policy. When a victim with an active session on the vulnerable Drupal site interacts with the attacker's content, the malicious script executes within the context of the vulnerable application.

The exploitation flow typically involves:

1. Attacker identifies a Drupal site using a vulnerable version of the Next.js module
2. Attacker crafts a malicious payload that leverages the permissive cross-domain policy
3. Victim is lured to visit the attacker-controlled content or a page containing the malicious payload
4. The victim's browser executes the script in the context of the trusted Drupal application
5. Attacker gains access to session tokens, user data, or can perform actions as the authenticated user

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

Detection Methods for CVE-2025-13984

Indicators of Compromise

• Unexpected cross-origin requests originating from or targeting the Drupal Next.js integration
• Unusual JavaScript execution patterns in browser developer console logs related to cross-domain communications
• Suspicious modifications to CORS headers or cross-domain policy configurations
• Reports of session hijacking or unauthorized actions from authenticated users

Detection Strategies

• Audit web server logs for abnormal cross-origin requests patterns, particularly those involving untrusted domains
• Implement Content Security Policy (CSP) reporting to monitor and alert on policy violations
• Deploy web application firewall (WAF) rules to detect and block common XSS attack patterns
• Review browser console logs for cross-origin related errors or unexpected script executions

Monitoring Recommendations

• Enable detailed logging for the Drupal Next.js module and monitor for configuration changes
• Implement real-time alerting for CSP violations that may indicate exploitation attempts
• Monitor user session activity for signs of hijacking or unauthorized access patterns
• Regularly audit cross-domain security policy configurations for unauthorized modifications

How to Mitigate CVE-2025-13984

Immediate Actions Required

• Update Drupal Next.js module to version 1.6.4 or later for the 1.x branch
• Update Drupal Next.js module to version 2.0.1 or later for the 2.x branch
• Review and audit current cross-domain security policy configurations
• Implement strict Content Security Policy headers to mitigate XSS risks

Patch Information

Drupal has released security patches addressing this vulnerability. Organizations running affected versions should update immediately:

• For versions 0.0.0 through 1.6.3: Upgrade to version 1.6.4 or later
• For version 2.0.0: Upgrade to version 2.0.1 or later

Detailed patch information and upgrade instructions are available in the Drupal Security Advisory.

Workarounds

• Implement strict Content Security Policy (CSP) headers to restrict script sources and mitigate XSS attacks
• Configure web application firewall (WAF) rules to block suspicious cross-origin requests
• Disable or restrict the Next.js module functionality until patches can be applied if immediate updating is not possible
• Review and harden CORS configurations to explicitly allow only trusted domains

# Example: Add Content Security Policy headers in Apache configuration
# Add to .htaccess or Apache virtual host configuration
Header set Content-Security-Policy "default-src 'self'; script-src 'self'; frame-ancestors 'self';"

# Example: Add Content Security Policy headers in Nginx configuration
# Add to nginx server block
add_header Content-Security-Policy "default-src 'self'; script-src 'self'; frame-ancestors 'self';" always;