CVE-2025-11687: gi-docgen XSS Vulnerability

CVE-2025-11687 Overview

A reflected DOM-based Cross-Site Scripting (XSS) vulnerability has been discovered in gi-docgen, the documentation generator for GObject-based libraries. This flaw allows attackers to execute arbitrary JavaScript in the context of the affected page through a crafted URL containing a malicious value in the q GET parameter. Successful exploitation enables DOM access, session cookie theft, and other client-side attacks against users who visit the malicious link.

Critical Impact

Attackers can steal session cookies, access sensitive DOM content, and perform actions on behalf of authenticated users through crafted URLs targeting gi-docgen documentation pages.

Affected Products

• gi-docgen (GNOME documentation generator)
• Documentation sites generated with vulnerable gi-docgen versions
• Systems hosting gi-docgen generated documentation

Discovery Timeline

• 2026-01-26 - CVE CVE-2025-11687 published to NVD
• 2026-01-27 - Last updated in NVD database

Technical Details for CVE-2025-11687

Vulnerability Analysis

This vulnerability is classified as CWE-79 (Improper Neutralization of Input During Web Page Generation), specifically a reflected DOM-based XSS flaw. The vulnerability exists in gi-docgen's search functionality, where user-supplied input through the q GET parameter is processed and reflected back into the page without proper sanitization or encoding.

Unlike traditional reflected XSS where the server reflects malicious content, DOM-based XSS occurs entirely on the client side. The JavaScript code in gi-docgen documentation pages reads the q parameter value and writes it to the DOM in an unsafe manner, allowing attackers to inject and execute arbitrary scripts. This type of vulnerability bypasses server-side security controls since the malicious payload never reaches the server in the processed form.

The network-accessible nature of this vulnerability, combined with the requirement for user interaction (clicking a malicious link), makes it suitable for phishing campaigns targeting developers and users who rely on gi-docgen generated documentation.

Root Cause

The root cause stems from insufficient input validation and output encoding in the search functionality of gi-docgen generated documentation pages. When the q parameter value is extracted from the URL and inserted into the DOM, it is not properly sanitized or escaped. This allows specially crafted payloads containing JavaScript code to be interpreted and executed by the browser rather than being displayed as text.

The vulnerability specifically occurs when:

1. A user visits a documentation page with a malicious q parameter
2. Client-side JavaScript extracts the parameter value
3. The unsanitized value is inserted into the DOM using unsafe methods
4. The browser executes the injected JavaScript code

Attack Vector

The attack vector is network-based, requiring an attacker to craft a malicious URL and convince a victim to click it. The attacker constructs a URL pointing to a gi-docgen generated documentation site with a specially crafted q parameter containing JavaScript payload. When a victim clicks this link, the malicious script executes in their browser context with full access to the page's DOM, cookies, and session data.

Typical attack scenarios include:

• Phishing emails containing malicious documentation links
• Social media posts sharing "helpful" documentation links
• Watering hole attacks targeting developer communities
• Injection of malicious links in forums or issue trackers

The vulnerability requires user interaction, which somewhat limits its severity, but the potential for session hijacking and credential theft makes it a significant security concern for documentation hosting environments.

Detection Methods for CVE-2025-11687

Indicators of Compromise

• Unusual URL patterns in web server logs containing encoded JavaScript in the q parameter
• Access logs showing documentation URLs with suspicious query strings containing script tags or event handlers
• Client-side error logs indicating unexpected script execution
• Reports of unexpected redirects or behavior from documentation page users

Detection Strategies

• Implement Content Security Policy (CSP) headers to detect and block inline script execution attempts
• Monitor web application firewall (WAF) logs for XSS attack patterns in query parameters
• Enable browser-based XSS auditing and monitor for triggered protections
• Review access logs for encoded payloads such as %3Cscript%3E, javascript:, or event handler injections in query strings

Monitoring Recommendations

• Configure real-time alerting for CSP violation reports from documentation hosting servers
• Set up log analysis rules to flag requests with suspicious patterns in the q parameter
• Monitor for unusual spikes in traffic to documentation search endpoints
• Implement user behavior analytics to detect potential session hijacking following XSS exploitation

How to Mitigate CVE-2025-11687

Immediate Actions Required

• Update gi-docgen to the latest patched version when available
• Implement strict Content Security Policy headers on documentation hosting servers to prevent inline script execution
• Review and audit any custom modifications to gi-docgen generated documentation
• Educate users about the risks of clicking untrusted documentation links

Patch Information

Refer to the GNOME Issue #228 Discussion for the latest patch information and updates from the gi-docgen maintainers. The Red Hat CVE-2025-11687 Advisory provides additional guidance for Red Hat-based distributions. Track Red Hat Bug Report #2403536 for distribution-specific patches.

Workarounds

• Deploy a Web Application Firewall (WAF) with XSS filtering rules to sanitize incoming q parameter values
• Implement strict Content Security Policy headers: Content-Security-Policy: default-src 'self'; script-src 'self'
• Restrict access to documentation pages to trusted networks where possible
• Consider temporarily disabling search functionality on public-facing documentation until a patch is applied

# Example CSP header configuration for Apache
# 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:; object-src 'none'; frame-ancestors 'none';"

# Example CSP header configuration for Nginx
# Add to server or location block
add_header Content-Security-Policy "default-src 'self'; script-src 'self'; style-src 'self' 'unsafe-inline'; img-src 'self' data:; object-src 'none'; frame-ancestors 'none';";