{
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "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\u0027s 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."
    }
  ],
  "id": "CVE-2026-44895",
  "lastModified": "2026-05-27T14:16:55.787",
  "metrics": {
    "cvssMetricV40": [
      {
        "cvssData": {
          "Automatable": "NOT_DEFINED",
          "Recovery": "NOT_DEFINED",
          "Safety": "NOT_DEFINED",
          "attackComplexity": "LOW",
          "attackRequirements": "PRESENT",
          "attackVector": "NETWORK",
          "availabilityRequirement": "NOT_DEFINED",
          "baseScore": 9.2,
          "baseSeverity": "CRITICAL",
          "confidentialityRequirement": "NOT_DEFINED",
          "exploitMaturity": "NOT_DEFINED",
          "integrityRequirement": "NOT_DEFINED",
          "modifiedAttackComplexity": "NOT_DEFINED",
          "modifiedAttackRequirements": "NOT_DEFINED",
          "modifiedAttackVector": "NOT_DEFINED",
          "modifiedPrivilegesRequired": "NOT_DEFINED",
          "modifiedSubAvailabilityImpact": "NOT_DEFINED",
          "modifiedSubConfidentialityImpact": "NOT_DEFINED",
          "modifiedSubIntegrityImpact": "NOT_DEFINED",
          "modifiedUserInteraction": "NOT_DEFINED",
          "modifiedVulnAvailabilityImpact": "NOT_DEFINED",
          "modifiedVulnConfidentialityImpact": "NOT_DEFINED",
          "modifiedVulnIntegrityImpact": "NOT_DEFINED",
          "privilegesRequired": "NONE",
          "providerUrgency": "NOT_DEFINED",
          "subAvailabilityImpact": "NONE",
          "subConfidentialityImpact": "NONE",
          "subIntegrityImpact": "NONE",
          "userInteraction": "NONE",
          "valueDensity": "NOT_DEFINED",
          "vectorString": "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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
          "version": "4.0",
          "vulnAvailabilityImpact": "LOW",
          "vulnConfidentialityImpact": "HIGH",
          "vulnIntegrityImpact": "HIGH",
          "vulnerabilityResponseEffort": "NOT_DEFINED"
        },
        "source": "security-advisories@github.com",
        "type": "Secondary"
      }
    ]
  },
  "published": "2026-05-26T22:16:42.730",
  "references": [
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/yoda-digital/mcp-gitlab-server/security/advisories/GHSA-8jr5-6gvj-rfpf"
    },
    {
      "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
      "url": "https://github.com/yoda-digital/mcp-gitlab-server/security/advisories/GHSA-8jr5-6gvj-rfpf"
    }
  ],
  "sourceIdentifier": "security-advisories@github.com",
  "vulnStatus": "Received",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-306"
        },
        {
          "lang": "en",
          "value": "CWE-942"
        }
      ],
      "source": "security-advisories@github.com",
      "type": "Secondary"
    }
  ]
}

{
  "affected": [
    {
      "package": {
        "ecosystem": "npm",
        "name": "@yoda.digital/gitlab-mcp-server"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "0.6.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-44895"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-306",
      "CWE-942"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-05-09T00:10:28Z",
    "nvd_published_at": null,
    "severity": "HIGH"
  },
  "details": "## SSE Transport Has No Authentication and Wildcard CORS, Exposing All 86 GitLab Tools Including Destructive Operations\n\nA review of `mcp-gitlab-server` at commit `80a7b4cf3fba6b55389c0ef491a48190f7c8996a` uncovered that the SSE HTTP transport \u2014 advertised in the README and comparison table as a differentiating feature \u2014 runs with no authentication and wildcard CORS on every endpoint. The maintainers\u0027 own roadmap confirms auth is a known gap.\n\nWhen `USE_SSE=true`, the HTTP server in `src/transport.ts` sets:\n\n```typescript\nres.setHeader(\u0027Access-Control-Allow-Origin\u0027, \u0027*\u0027);\nres.setHeader(\u0027Access-Control-Allow-Methods\u0027, \u0027GET, POST\u0027);\nres.setHeader(\u0027Access-Control-Allow-Headers\u0027, \u0027Content-Type\u0027);\n```\n\nThe `httpServer.listen(port)` call at line 97 passes no host argument \u2014 Node.js defaults to `0.0.0.0`, binding on all interfaces. Two endpoints are exposed with no credential check:\n\n- `GET /sse` \u2014 opens an SSE connection, returns a session endpoint URL\n- `POST /messages?sessionId=\u003cid\u003e` \u2014 sends MCP messages to the server using the loaded `GITLAB_PERSONAL_ACCESS_TOKEN`\n\nAny caller who can reach the port \u2014 LAN, cloud instance, or via the browser-tab vector the wildcard CORS enables \u2014 gets full access to all 86 tools the server exposes using the operator\u0027s GitLab PAT. That includes `delete_repository`, `delete_group`, `push_files`, `create_merge_request`, `update_repository_settings`, and any other tool the server exposes. The PAT doesn\u0027t leave the process, but every API call it backs is available to the unauthenticated caller.\n\nThe wildcard CORS makes the browser-tab vector direct: any web page the operator visits while the server is running can open an SSE connection and make tool calls via cross-origin fetch. No user interaction beyond visiting the page.\n\n**PoC \u2014 reproduces from the documented USE_SSE=true configuration:**\n\n```bash\n# Step 1: connect SSE and capture the session endpoint\ncurl -N http://localhost:3000/sse \u0026\n# Output includes: event: endpoint\n#                  data: /messages?sessionId=\u003cUUID\u003e\n\n# Step 2: call any tool \u2014 no auth header needed\ncurl -X POST \"http://localhost:3000/messages?sessionId=\u003cUUID\u003e\" \\\n  -H \"Content-Type: application/json\" \\\n  -d \u0027{\n    \"jsonrpc\": \"2.0\",\n    \"id\": 1,\n    \"method\": \"tools/call\",\n    \"params\": {\n      \"name\": \"get_repository\",\n      \"arguments\": {\"project_id\": \"target-org/private-repo\"}\n    }\n  }\u0027\n# Returns repository data using the operator\u0027s GitLab PAT\n\n# Same path works for delete_repository, push_files, etc.\n```\n\n## Root cause\n\nThe 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\u0027s `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. Auth isn\u0027t fail-opening on a missing config \u2014 there is no auth check at any code path on either `/sse` or `/messages?sessionId=...`.\n\n## Auth boundary violated\n\nTrust-domain boundary \u2014 untrusted cross-origin browser context (and any unauthenticated network caller) crossing into the trusted server-state-mutating GitLab API surface that the operator\u0027s PAT backs. Respected-here: nothing. The transport carries no `Authorization` check, no origin allowlist, no session-binding to the originating client, and no host restriction. Ignored-there: the SSE handler at `src/transport.ts` accepts an arbitrary `Origin` (since `Access-Control-Allow-Origin: *`), opens a session, and the matching `POST /messages?sessionId=...` proxies tool calls \u2014 including `delete_repository`, `push_files`, `update_repository_settings` \u2014 to the GitLab API using the operator\u0027s PAT. Any web page the operator visits while the server runs can drive the full 86-tool surface via cross-origin fetch.\n\nThe roadmap in `README.md` at line 190 includes `- [ ] SAML/OAuth3 authentication` \u2014 confirming the maintainers are already tracking this gap. The issue is disclosure of impact in the interim: operators who follow the README\u0027s SSE setup instructions and don\u0027t see an auth requirement in the docs may reasonably assume the transport is safe to use on a network-accessible host.\n\n**CVSS 4.0:** `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` \u2014 **~6.3 (Medium)**. `AT:P` reflects the `USE_SSE=true` precondition. When that precondition is met, the effective severity for those deployments is High \u2014 full GitLab PAT access without authentication. The Medium CVSS is the aggregate across all deployments; for any operator who has activated SSE mode (which the README promotes as a feature), the finding is functionally High.\n\n**Fix \u2014 four concrete changes:**\n\n1. Require `MCP_GITLAB_AUTH_TOKEN` as a startup precondition when `USE_SSE=true`. If the env var is unset, the server should exit with a clear message before the HTTP server starts:\n\n   ```typescript\n   if (process.env.USE_SSE === \u0027true\u0027) {\n     if (!process.env.MCP_GITLAB_AUTH_TOKEN) {\n       console.error(\n         \u0027ERROR: MCP_GITLAB_AUTH_TOKEN must be set when USE_SSE=true. \u0027 +\n         \u0027SSE transport without authentication exposes all GitLab tools to unauthenticated callers.\u0027\n       );\n       process.exit(1);\n     }\n   }\n   ```\n\n   The token check in `src/transport.ts` validates it on every request:\n   ```typescript\n   const authToken = process.env.MCP_GITLAB_AUTH_TOKEN;\n   if (authToken) {\n     const provided = req.headers[\u0027authorization\u0027]?.replace(/^Bearer /, \u0027\u0027);\n     if (provided !== authToken) {\n       res.writeHead(401);\n       res.end(JSON.stringify({ error: \u0027Unauthorized\u0027 }));\n       return;\n     }\n   }\n   ```\n\n2. Bind to `127.0.0.1` by default for the SSE transport rather than `0.0.0.0`. An explicit `MCP_GITLAB_HOST=0.0.0.0` flag with a startup banner warning can expose it to the network for operators who need that \u2014 but the safe default should be loopback-only.\n\n3. Replace the wildcard `Access-Control-Allow-Origin: *` with a localhost-only default. When network exposure is intentional (explicit flag + auth token set), an explicit `CORS_ORIGINS` allowlist should be required.\n\n4. The SAML/OAuth3 roadmap item is the right long-term direction. In the interim \u2014 before that ships \u2014 the three changes above are entirely in the existing codebase with no new dependencies.\n\n---\n\nNo prior security advisories, CVEs, or public security issues exist for this package \u2014 a search of the repository issue list and npm advisory database did not yield any duplicate issues.",
  "id": "GHSA-8jr5-6gvj-rfpf",
  "modified": "2026-05-09T00:10:28Z",
  "published": "2026-05-09T00:10:28Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/yoda-digital/mcp-gitlab-server/security/advisories/GHSA-8jr5-6gvj-rfpf"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/yoda-digital/mcp-gitlab-server"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:H/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "@yoda.digital/gitlab-mcp-server\u0027s SSE transport has no authentication and wildcard CORS, exposing all 86 GitLab tools"
}