CVE-2025-31675: Drupal Core XSS Vulnerability

CVE-2025-31675 Overview

CVE-2025-31675 is a Cross-Site Scripting (XSS) vulnerability in Drupal Core that stems from improper neutralization of input during web page generation. This vulnerability allows attackers with authenticated access to inject malicious scripts into web pages viewed by other users, potentially compromising user sessions, stealing sensitive data, or performing unauthorized actions on behalf of victims.

The vulnerability affects multiple major versions of Drupal core, spanning from version 8.0.0 through various 10.x and 11.x releases, making it a significant concern for organizations running Drupal-based websites and applications.

Critical Impact

Authenticated attackers can execute arbitrary JavaScript in the context of victim user sessions, potentially leading to session hijacking, credential theft, and unauthorized actions within Drupal installations.

Affected Products

• Drupal Core versions 8.0.0 to 10.3.13
• Drupal Core versions 10.4.0 to 10.4.4
• Drupal Core versions 11.0.0 to 11.0.12
• Drupal Core versions 11.1.0 to 11.1.4

Discovery Timeline

• 2025-03-31 - CVE-2025-31675 published to NVD
• 2025-06-02 - Last updated in NVD database

Technical Details for CVE-2025-31675

Vulnerability Analysis

This XSS vulnerability exists due to insufficient input validation and output encoding within Drupal Core's web page generation mechanisms. When user-supplied input is processed and rendered without proper sanitization, it creates an opportunity for attackers to inject malicious script content that executes in the browsers of other users.

The vulnerability requires the attacker to have low-level privileges (authenticated access) on the target Drupal installation. Additionally, successful exploitation requires user interaction—a victim must view the page containing the injected malicious content. Due to the scope change characteristic of this vulnerability, the impact extends beyond the vulnerable component itself, potentially affecting other components or user sessions.

The attack results in limited confidentiality and integrity impact, allowing attackers to potentially access sensitive information displayed to users or modify content within the context of the victim's session. No availability impact has been identified with this vulnerability.

Root Cause

The root cause of CVE-2025-31675 is classified under CWE-79 (Improper Neutralization of Input During Web Page Generation). This occurs when the application fails to properly validate, filter, or encode user-controllable input before it is placed in output that is used as a web page served to other users.

In Drupal's case, specific input fields or content areas do not adequately sanitize user input before rendering it in the HTML output, allowing script tags or event handlers to be injected and subsequently executed.

Attack Vector

The attack vector for this vulnerability is network-based, requiring authenticated access to the Drupal installation. An attacker would typically:

1. Authenticate to the vulnerable Drupal installation with minimal privileges
2. Identify input fields or content areas susceptible to XSS injection
3. Craft malicious JavaScript payloads designed to execute when viewed by other users
4. Submit the payload through the vulnerable input mechanism
5. Wait for victim users to access the page containing the injected script

The vulnerability mechanism involves improper neutralization of special characters in user input. When a victim user views the affected page, the injected script executes within their browser context, potentially allowing the attacker to steal session cookies, capture keystrokes, redirect users to malicious sites, or perform actions on behalf of the victim. For detailed technical information, refer to the Drupal Security Advisory SA-CORE-2025-004.

Detection Methods for CVE-2025-31675

Indicators of Compromise

• Unexpected JavaScript code or <script> tags appearing in user-generated content or database fields
• Unusual inline event handlers (onclick, onload, onerror) in stored content
• Session anomalies or unauthorized actions performed by legitimate user accounts
• Browser console errors indicating blocked XSS attempts by Content Security Policy
• Reports from users of unexpected pop-ups, redirects, or behavior on Drupal pages

Detection Strategies

• Implement Web Application Firewall (WAF) rules to detect common XSS payload patterns in requests
• Enable Content Security Policy (CSP) headers with report-uri to capture blocked XSS attempts
• Deploy application-level logging to monitor for suspicious input patterns containing script content
• Utilize SentinelOne Singularity platform to detect anomalous browser behavior and script execution patterns

Monitoring Recommendations

• Regularly audit Drupal logs for authentication events followed by content modification activities
• Monitor database content for injection of unexpected HTML or JavaScript elements
• Implement automated vulnerability scanning to identify unpatched Drupal installations
• Enable real-time alerting for CSP violation reports indicating potential XSS exploitation attempts

How to Mitigate CVE-2025-31675

Immediate Actions Required

• Upgrade Drupal Core to version 10.3.14, 10.4.5, 11.0.13, or 11.1.5 depending on your current branch
• Review user-generated content for signs of injected malicious scripts
• Implement Content Security Policy headers to reduce XSS impact
• Audit user accounts with content creation privileges for suspicious activity
• Consider temporarily restricting content creation capabilities until patches are applied

Patch Information

Drupal has released security updates addressing CVE-2025-31675. Organizations should apply the appropriate patch based on their current Drupal version:

• For Drupal 10.3.x: Upgrade to version 10.3.14 or later
• For Drupal 10.4.x: Upgrade to version 10.4.5 or later
• For Drupal 11.0.x: Upgrade to version 11.0.13 or later
• For Drupal 11.1.x: Upgrade to version 11.1.5 or later

Detailed patch information is available in the Drupal Security Advisory SA-CORE-2025-004.

Workarounds

• Implement strict Content Security Policy (CSP) headers to prevent inline script execution
• Use a Web Application Firewall (WAF) with XSS protection rules enabled
• Restrict content creation and editing permissions to trusted users only
• Enable HttpOnly and Secure flags on session cookies to limit impact of successful XSS attacks
• Consider using Drupal's text format filtering to restrict allowed HTML elements

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

# Enable HttpOnly and Secure flags for cookies in settings.php
# ini_set('session.cookie_httponly', 1);
# ini_set('session.cookie_secure', 1);