Vulnerability · Published Jul 9, 2026 · Assigned by GitHub_M
CVE-2026-55605@arikusi/deepseek-mcp-server Missing Authentication on Self-Hosted HTTP MCP Endpoint
Medium 5.3
In plain English
A medium-severity missing authentication in deepseek-mcp-server from arikusi. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 44% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| npm | @arikusi/deepseek-mcp-server | 1.8.0 | GHSA-72f3-6w86-7rv3 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| arikusi | deepseek-mcp-server | >= 1.4.2, < 1.8.0 |
Weakness: CWE-306 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L