CVE-2025-8405
📋 TL;DR
This vulnerability in GitLab allows authenticated users to inject malicious HTML into vulnerability code flow displays, enabling them to perform unauthorized actions on behalf of other users. It affects GitLab Community Edition (CE) and Enterprise Edition (EE) installations running vulnerable versions. Attackers could potentially manipulate other users' sessions or perform actions without proper authorization.
💻 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 →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
An attacker could perform administrative actions, access sensitive data, modify repositories, or compromise user accounts by exploiting session hijacking or privilege escalation through the HTML injection.
Likely Case
Attackers with authenticated access could perform unauthorized actions in the context of other users, potentially leading to data leakage, repository manipulation, or privilege escalation within the GitLab instance.
If Mitigated
With proper access controls and monitoring, impact would be limited to isolated incidents that could be detected and contained through existing security controls.
🎯 Exploit Status
Exploitation requires authenticated access and knowledge of HTML injection techniques. The vulnerability is in the vulnerability code flow display feature.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 18.4.6, 18.5.4, or 18.6.2
Vendor Advisory: https://about.gitlab.com/releases/2025/12/10/patch-release-gitlab-18-6-2-released/
Restart Required: Yes
Instructions:
1. Backup your GitLab instance. 2. Update to GitLab 18.4.6, 18.5.4, or 18.6.2 depending on your current version. 3. Restart GitLab services. 4. Verify the update was successful.
🔧 Temporary Workarounds
Disable vulnerability code flow displays
allTemporarily disable the vulnerability code flow display feature to prevent exploitation
gitlab-rails console
Feature.disable(:vulnerability_code_flow_display)
🧯 If You Can't Patch
- Restrict user access to only trusted individuals and implement strict access controls
- Enable enhanced logging and monitoring for suspicious activity in vulnerability-related features
🔍 How to Verify
Check if Vulnerable:
Check your GitLab version using: sudo gitlab-rake gitlab:env:info | grep 'GitLab version'Check Version:
sudo gitlab-rake gitlab:env:info | grep 'GitLab version'Verify Fix Applied:
After patching, verify version is 18.4.6, 18.5.4, or 18.6.2 or higher using: sudo gitlab-rake gitlab:env:info | grep 'GitLab version'📡 Detection & Monitoring
Log Indicators:
- Unusual HTML content in vulnerability code flow requests
- Multiple failed authentication attempts followed by successful access
- Unexpected user privilege changes
Network Indicators:
- Unusual patterns in API calls to vulnerability endpoints
- Suspicious HTML payloads in HTTP requests
SIEM Query:
source="gitlab" AND (message="vulnerability_code_flow" OR message="HTML injection")