{"id":"CVE-2026-55605","aliases":["GHSA-72f3-6w86-7rv3"],"url":"https://o3.security/vulnerability/CVE-2026-55605","summary":"@arikusi/deepseek-mcp-server Missing Authentication on Self-Hosted HTTP MCP Endpoint","details":"DeepSeek MCP Server is an MCP server for DeepSeek V4. Starting in version 1.4.2 and prior to version 1.8.0, the self-hosted HTTP transport of `@arikusi/deepseek-mcp-server` exposes `POST /mcp` without any authentication: `createMcpExpressApp` is called without an `authProvider` and no middleware guards the route, so any network-reachable client can issue an unauthenticated `initialize` request and obtain a valid MCP session identifier. In reproduced testing against commit `5e1302171e99`, an unauthenticated client was able to initialize a session, enumerate tools, and invoke the local `deepseek_sessions` tool with no credentials. The same unauthenticated session also exposes `deepseek_chat`, whose handler uses the server-side `DEEPSEEK_API_KEY` when self-hosted deployments configure one. This issue applies to self-hosted HTTP mode, not the separately documented hosted BYOK endpoint in `README.md`, which expects an `Authorization: Bearer ...` header. Upstream self-hosted container assets enable HTTP mode by default (`Dockerfile`) and publish port `3000` (`docker-compose.yml`). Version 1.8.0 contains a patch for this issue.","published":"2026-07-09T21:10:53.882Z","modified":"2026-08-12T03:51:38.605455491Z","cvss":{"score":5.3,"severity":"MEDIUM","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L"},"epss":null,"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"npm","name":"@arikusi/deepseek-mcp-server","fixedVersion":"1.8.0"}],"fix":null,"references":[{"type":"WEB","url":"https://github.com/arikusi/deepseek-mcp-server/blob/main/CHANGELOG.md#180---2026-06-14"},{"type":"WEB","url":"https://github.com/arikusi/deepseek-mcp-server/releases/tag/v1.8.0"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/55xxx/CVE-2026-55605.json"},{"type":"ADVISORY","url":"https://github.com/arikusi/deepseek-mcp-server/security/advisories/GHSA-72f3-6w86-7rv3"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-55605"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-12T03:51:38.605455491Z"}}