@arikusi/deepseek-mcp-server: Missing Authentication on Self-Hosted HTTP MCP Endpoint

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

5.3 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

EPSS

• CVE-2026-55605: 0.52% estimated exploitation activity in the next 30 days; percentile 44.18 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary 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 deepseeksessions tool with no credentials. The same unauthenticated session also exposes deepseekchat, whose handler uses the server-side DEEPSEEKAPIKEY 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). Affected Code src/transport-http.ts:17…

Published by the source

25 Aug 2026, 18:38 UTC

Last modified by the source

1 Oct 2026, 08:56 UTC

Source last checked

26 Oct 2026, 13:06 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-72f3-6w86-7rv3

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# Patch Next advisory brief: CVE-2026-55605

Advisory: @arikusi/deepseek-mcp-server: Missing Authentication on Self-Hosted HTTP MCP Endpoint
IDs: CVE-2026-55605, GHSA-72f3-6w86-7rv3
Record: https://patchnext.com/advisories/cve-2026-55605 (revision 1, source checked 26 Oct 2026, 13:06 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.3)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: @arikusi/deepseek-mcp-server 1.8.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm @arikusi/deepseek-mcp-server: affected >= 1.4.2, < 1.8.0; fixed in 1.8.0

## Suggested inspection (read-only)
- `npm ls @arikusi/deepseek-mcp-server --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on @arikusi/deepseek-mcp-server.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-72f3-6w86-7rv3 (GitHub-reviewed advisory GHSA-72f3-6w86-7rv3 lists affected ranges: npm @arikusi/deepseek-mcp-server >=1.4.2 <1.8.0)

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