CVE-2026-44895
GitLab MCP Server: SSE transport has no authentication and wildcard CORS, exposing all GitLab tools
- State
- Published
- Severity
- 9.2 Critical
- Published
- May 26, 2026
- Updated
- May 27, 2026
- Reserved
- May 7, 2026
Description
GitLab MCP Server lets an AI agent talk directly to GitLab. Prior to 0.6.0, the HTTP transport in src/transport.ts ships with no authentication layer at all and a wildcard Access-Control-Allow-Origin: * on every response. The structural defect is that the SSE server stands up a stateful, mutation-capable RPC endpoint that is backed by the operator's GITLAB_PERSONAL_ACCESS_TOKEN without any inbound credential check, then advertises itself to every cross-origin browser context via the wildcard CORS header. The httpServer.listen(port) call at line 97 also passes no host argument, so the bind defaults to 0.0.0.0 and exposes the auth-less surface on every interface. This vulnerability is fixed in 0.6.0.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 4.0 | 9.2 Critical | CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:L/SC:N/SI:N/SA:N | GitHub_M |
Weaknesses
Affected Products
| Product | Versions |
|---|---|
mcp-gitlab-serveryoda-digital |
|
References
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