CVE-2026-44895
GitLab MCP Server Missing Authentication in HTTP Transport
Publication date: 2026-05-26
Last updated on: 2026-05-26
Assigner: GitHub, Inc.
Description
Description
CVSS Scores
EPSS Scores
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Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| gitlab | mcp_server | to 0.6.0 (inc) |
Helpful Resources
Exploitability
| CWE ID | Description |
|---|---|
| CWE-942 | The product uses a web-client protection mechanism such as a Content Security Policy (CSP) or cross-domain policy file, but the policy includes untrusted domains with which the web client is allowed to communicate. |
| CWE-306 | The product does not perform any authentication for functionality that requires a provable user identity or consumes a significant amount of resources. |
Attack-Flow Graph
AI Powered Q&A
Can you explain this vulnerability to me?
This vulnerability exists in GitLab MCP Server versions prior to 0.6.0. The HTTP transport component in the source code (src/transport.ts) lacks any authentication layer and uses a wildcard Access-Control-Allow-Origin: * header on every response. This means that the server exposes a stateful, mutation-capable RPC endpoint that uses the operator's GitLab personal access token without verifying inbound credentials. Additionally, the server listens on all network interfaces (0.0.0.0) without restricting access. As a result, any cross-origin browser context can access this endpoint, potentially allowing unauthorized actions using the operator's credentials.
How can this vulnerability impact me? :
The vulnerability can lead to unauthorized access and control over the GitLab MCP Server because the RPC endpoint is exposed without authentication and accessible from any origin. An attacker could exploit this to perform mutations or actions on behalf of the operator using their personal access token, potentially leading to data manipulation, unauthorized changes, or compromise of the GitLab environment.
What immediate steps should I take to mitigate this vulnerability?
The vulnerability is fixed in GitLab MCP Server version 0.6.0. Immediate mitigation involves upgrading the GitLab MCP Server to version 0.6.0 or later.
Prior to upgrading, be aware that the vulnerable versions expose an unauthenticated RPC endpoint bound to all interfaces (0.0.0.0) with a wildcard Access-Control-Allow-Origin header, which allows cross-origin access without credential checks.
- Upgrade GitLab MCP Server to version 0.6.0 or later.
- Restrict network access to the server to trusted hosts only, to limit exposure.
- Avoid exposing the vulnerable service to public or untrusted networks until patched.
How does this vulnerability affect compliance with common standards and regulations (like GDPR, HIPAA)?:
The vulnerability allows unauthenticated access to a stateful, mutation-capable RPC endpoint backed by an operator's personal access token, exposed on every network interface with a wildcard CORS policy. This could lead to unauthorized access and potential data breaches.
Such unauthorized access and exposure of sensitive tokens could result in non-compliance with data protection regulations like GDPR and HIPAA, which require strict access controls and protection of personal and sensitive data.