A critical vulnerability in zereight gitlab-mcp allows unauthenticated remote attackers to perform arbitrary file reads, leading to full GitLab account compromise.

The application fails to perform authentication when using SSE transport mode and contains a path traversal vulnerability in the upload_markdown tool, which allows unauthenticated attackers to read arbitrary files from the local filesystem.

This vulnerability presents a severe risk to organizational security, as it enables unauthenticated attackers to exfiltrate sensitive environment variables, including GitLab personal access tokens. Successful exploitation grants attackers full control over affected GitLab accounts, potentially leading to unauthorized code access, data exfiltration, and supply chain compromise. Given the CVSS score of 9.8, this flaw is considered critical and requires immediate attention to prevent total system compromise.

Immediate Action: Update the zereight gitlab-mcp package to version 2.1.27 or later immediately to resolve the authentication bypass and path traversal vulnerabilities.

Proactive Monitoring: Review server access logs for anomalous requests to the SSE transport endpoint and monitor for unexpected file access patterns or suspicious activity involving the upload_markdown tool.

Compensating Controls: If immediate patching is not feasible, restrict network access to the gitlab-mcp service using a firewall or VPN to ensure it is not exposed to untrusted networks or the public internet.

Public Exploit Available: Unknown

The severity of this vulnerability cannot be overstated, as it provides a direct path for attackers to gain administrative control over GitLab environments. Organizations utilizing gitlab-mcp must prioritize the update to version 2.1.27 as their primary security objective. Failure to apply this patch leaves the infrastructure exposed to trivial account takeover attacks that bypass all standard security controls.