CVE-2025-2255
📋 TL;DR
This vulnerability allows Cross-Site Scripting (XSS) attacks through error messages in GitLab's AppSec feature. Attackers can inject malicious scripts that execute in users' browsers when they view certain error messages. All GitLab EE/CE instances with AppSec enabled in affected versions are vulnerable.
💻 Affected Systems
- GitLab EE
- GitLab CE
📦 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 →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
Attackers could steal session cookies, perform actions as authenticated users, redirect to malicious sites, or install malware on user systems through browser exploitation.
Likely Case
Session hijacking, credential theft, or unauthorized actions performed in the context of authenticated users who view malicious error messages.
If Mitigated
Limited impact if Content Security Policy (CSP) is properly configured and users have script blockers, though some XSS may still bypass these controls.
🎯 Exploit Status
Exploitation requires ability to trigger specific error messages with malicious payloads. May require some authentication or specific conditions.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 17.8.6, 17.9.3, or 17.10.1
Vendor Advisory: https://gitlab.com/gitlab-org/gitlab/-/issues/524635
Restart Required: No
Instructions:
1. Backup your GitLab instance. 2. Update to patched version: 17.8.6, 17.9.3, or 17.10.1. 3. Verify update completed successfully. 4. Test AppSec functionality.
🔧 Temporary Workarounds
Disable AppSec Feature
allTemporarily disable the AppSec feature to prevent exploitation while planning upgrade.
gitlab-rails runner "Feature.disable(:security_dashboard)"
🧯 If You Can't Patch
- Implement strict Content Security Policy (CSP) headers to limit script execution
- Use web application firewall (WAF) rules to block XSS payloads in error messages
🔍 How to Verify
Check if Vulnerable:
Check GitLab version via Admin Area or command line. If version falls in affected ranges and AppSec is enabled, instance is vulnerable.Check Version:
sudo gitlab-rake gitlab:env:info | grep 'Version:'Verify Fix Applied:
Confirm version is 17.8.6, 17.9.3, or 17.10.1 or higher. Test AppSec error message functionality.📡 Detection & Monitoring
Log Indicators:
- Unusual error messages containing script tags or JavaScript in AppSec logs
- Multiple failed AppSec operations from single user
Network Indicators:
- HTTP requests containing script payloads in error message parameters
- Unexpected redirects from AppSec pages
SIEM Query:
source="gitlab" AND ("AppSec" OR "security_dashboard") AND ("error" OR "exception") AND ("script" OR "javascript" OR "onload" OR "onerror")