CVE-2025-11687 is a reflected DOM-based Cross-site Scripting (XSS) vulnerability identified in the gi-docgen tool, a documentation generator. The vulnerability arises from improper neutralization of input during web page generation, specifically through the 'q' GET parameter. An attacker can craft a malicious URL embedding JavaScript code within this parameter, which is then reflected unsanitized in the DOM, enabling execution of arbitrary scripts in the victim's browser context. This can lead to session cookie theft, unauthorized DOM manipulation, and other client-side attacks such as phishing or malware delivery. The vulnerability does not require authentication but does require user interaction, such as clicking a malicious link. The CVSS 3.1 base score is 6.1, reflecting medium severity due to network attack vector, low attack complexity, no privileges required, but user interaction needed, and partial impact on confidentiality and integrity. No known exploits have been reported in the wild yet. The affected version is 0 of gi-docgen, which suggests early or initial releases of the tool. The vulnerability was published on January 26, 2026, with the CVE reserved in October 2025. The flaw is significant for environments where gi-docgen is used to generate web-accessible documentation, especially if exposed to external or untrusted users. Attackers could leverage this to compromise users viewing the documentation, potentially leading to broader network compromise if session tokens or credentials are stolen.

For European organizations, the impact of CVE-2025-11687 primarily involves client-side security risks to users accessing documentation generated by gi-docgen. If the documentation is publicly accessible or shared with external partners, attackers could exploit the vulnerability to execute malicious scripts, leading to session hijacking, credential theft, or delivery of further malware. This can compromise user accounts and potentially provide a foothold for lateral movement within corporate networks. Organizations relying on gi-docgen for internal documentation may face insider threats if malicious links are circulated internally. The medium severity score indicates moderate risk, but the actual impact depends on exposure level and user base. Confidentiality and integrity of user sessions are at risk, while availability is not directly affected. The lack of known exploits reduces immediate threat but does not eliminate future risk. European companies in sectors with high regulatory requirements for data protection (e.g., finance, healthcare) could face compliance issues if user data is compromised through this vulnerability.

To mitigate CVE-2025-11687, organizations should first verify if they use gi-docgen version 0 or any affected versions and plan for an upgrade or patch once available. In the absence of an official patch, implement strict input validation and output encoding on the 'q' GET parameter to neutralize any malicious scripts before rendering in the DOM. Employ Content Security Policy (CSP) headers to restrict execution of unauthorized scripts on documentation pages. Limit access to documentation portals to trusted users and networks, using authentication and network segmentation where possible. Educate users about the risks of clicking untrusted links, especially those pointing to documentation URLs. Monitor web server logs for suspicious query parameters and unusual access patterns. Consider deploying web application firewalls (WAFs) with custom rules to detect and block XSS payloads targeting the 'q' parameter. Regularly review and update security controls as patches and advisories are released by gi-docgen maintainers.