CVE-2025-13761
📋 TL;DR
This is a cross-site scripting (XSS) vulnerability in GitLab that allows an unauthenticated attacker to execute arbitrary JavaScript code in the context of an authenticated user's browser by tricking them into visiting a malicious webpage. All GitLab CE/EE instances running affected versions are vulnerable, potentially compromising user sessions and data.
💻 Affected Systems
- GitLab Community Edition
- GitLab Enterprise Edition
📦 What is this software?
Gitlab by Gitlab
GitLab is a complete DevOps platform providing source code management, CI/CD pipelines, security scanning, container registry, and collaboration tools used by millions of developers and thousands of enterprises worldwide. As both a cloud-hosted SaaS offering (GitLab.com) and self-managed software, G...
Learn more about Gitlab →Gitlab by Gitlab
GitLab is a complete DevOps platform providing source code management, CI/CD pipelines, security scanning, container registry, and collaboration tools used by millions of developers and thousands of enterprises worldwide. As both a cloud-hosted SaaS offering (GitLab.com) and self-managed software, G...
Learn more about Gitlab →Gitlab by Gitlab
GitLab is a complete DevOps platform providing source code management, CI/CD pipelines, security scanning, container registry, and collaboration tools used by millions of developers and thousands of enterprises worldwide. As both a cloud-hosted SaaS offering (GitLab.com) and self-managed software, G...
Learn more about Gitlab →Gitlab by Gitlab
GitLab is a complete DevOps platform providing source code management, CI/CD pipelines, security scanning, container registry, and collaboration tools used by millions of developers and thousands of enterprises worldwide. As both a cloud-hosted SaaS offering (GitLab.com) and self-managed software, G...
Learn more about Gitlab →⚠️ Risk & Real-World Impact
Worst Case
Complete account takeover, data theft, privilege escalation, and lateral movement within the GitLab instance through authenticated user sessions.
Likely Case
Session hijacking, data exfiltration, and unauthorized actions performed as the victim user within GitLab.
If Mitigated
Limited impact with proper CSP headers, session timeouts, and user awareness training, though code execution in browser context still occurs.
🎯 Exploit Status
Exploitation requires social engineering (convincing user to visit malicious page) but no authentication to GitLab. The CWE-79 classification indicates classic XSS exploitation patterns.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 18.6.3 or 18.7.1
Vendor Advisory: https://about.gitlab.com/releases/2026/01/07/patch-release-gitlab-18-7-1-released/
Restart Required: Yes
Instructions:
1. Backup your GitLab instance. 2. Update to GitLab 18.6.3 (if on 18.6.x) or 18.7.1 (if on 18.7.x). 3. Restart GitLab services. 4. Verify the update completed successfully.
🔧 Temporary Workarounds
Content Security Policy (CSP) Enhancement
allImplement strict CSP headers to mitigate XSS impact by restricting script execution sources.
# Add to GitLab configuration (gitlab.rb):
gitlab_rails['content_security_policy'] = {
'default-src' => "'self'",
'script-src' => "'self' 'unsafe-inline' 'unsafe-eval'",
'style-src' => "'self' 'unsafe-inline'",
'img-src' => "'self' data: https:",
'font-src' => "'self'",
'connect-src' => "'self'",
'frame-src' => "'none'",
'object-src' => "'none'"
}
🧯 If You Can't Patch
- Isolate GitLab instance from internet access and restrict to internal network only.
- Implement web application firewall (WAF) rules to block XSS payloads and monitor for exploitation attempts.
🔍 How to Verify
Check if Vulnerable:
Check GitLab version via Admin Area or command line. If version is between 18.6.0-18.6.2 or exactly 18.7.0, the instance is vulnerable.Check Version:
sudo gitlab-rake gitlab:env:info | grep 'Version:'Verify Fix Applied:
After patching, confirm version is 18.6.3 or 18.7.1 and test that the specific XSS vector from references is no longer exploitable.📡 Detection & Monitoring
Log Indicators:
- Unusual JavaScript execution errors in browser console logs
- Suspicious referrer headers pointing to external domains in access logs
- Multiple failed authentication attempts followed by successful login from same IP
Network Indicators:
- Outbound connections to unknown domains from GitLab server
- Unusual traffic patterns to GitLab instance from suspicious sources
SIEM Query:
source="gitlab_access.log" AND (uri="*<script>*" OR referer="*malicious-domain*" OR status=200 AND user_agent="*Mozilla*" AND bytes>1000000)