CVE-2023-6688
📋 TL;DR
This vulnerability in GitLab's Google Chat Messages integration allows attackers to cause a denial-of-service (DoS) condition through a regular expression attack. All GitLab CE/EE instances from version 16.11 to 16.11.1 are affected. The attack targets the server's processing logic for Google Chat messages.
💻 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 →⚠️ Risk & Real-World Impact
Worst Case
Complete service unavailability due to server resource exhaustion, potentially affecting all GitLab services including repositories, CI/CD pipelines, and user authentication.
Likely Case
Temporary service degradation or unavailability of the GitLab instance, disrupting development workflows and collaboration.
If Mitigated
Minimal impact with proper rate limiting, monitoring, and quick detection of anomalous patterns in Google Chat message processing.
🎯 Exploit Status
Exploitation requires sending specially crafted messages to the Google Chat integration endpoint. Attackers need access to send messages to the integrated Google Chat channel.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 16.11.2
Vendor Advisory: https://gitlab.com/gitlab-org/gitlab/-/issues/434854
Restart Required: Yes
Instructions:
1. Backup your GitLab instance. 2. Update GitLab to version 16.11.2 or later using your package manager. 3. Restart GitLab services. 4. Verify the update was successful.
🔧 Temporary Workarounds
Disable Google Chat Integration
allTemporarily disable the Google Chat Messages integration to prevent exploitation.
Navigate to Admin Area > Settings > Integrations > Google Chat and disable the integration
Implement Rate Limiting
linuxConfigure rate limiting for Google Chat integration endpoints to reduce DoS impact.
Configure nginx or similar proxy to limit requests to /api/v4/integrations/google_chat endpoints
🧯 If You Can't Patch
- Disable Google Chat Messages integration immediately
- Implement network-level controls to restrict access to Google Chat integration endpoints
🔍 How to Verify
Check if Vulnerable:
Check GitLab version: if between 16.11 and 16.11.1 and Google Chat integration is enabled, the system is vulnerable.Check Version:
sudo gitlab-rake gitlab:env:info | grep 'GitLab version'Verify Fix Applied:
Verify GitLab version is 16.11.2 or later and test Google Chat integration functionality.📡 Detection & Monitoring
Log Indicators:
- Unusual patterns of Google Chat integration requests
- High CPU/memory usage on GitLab server
- Timeout errors in Google Chat integration logs
Network Indicators:
- Abnormal traffic patterns to /api/v4/integrations/google_chat endpoints
- Multiple rapid requests to Google Chat integration
SIEM Query:
source="gitlab.log" AND "Google Chat" AND ("timeout" OR "error" OR "high load")