dbcve.org
Missing AuthenticationWeakness · CWE-306

CVE-2026-55605

MEDIUM · 5.3 CVSS v3.1 Published 2026-07-09
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
62/100
Remediation priority · Elevated
Remotely reachable No privileges Zero-click 6 weeks old

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

DeepSeek MCP Server versions 1.4.2 through 1.8.0 have an authentication bypass in the self-hosted HTTP transport. The `createMcpExpressApp` function is called without an `authProvider` and no middleware protects the `POST /mcp` endpoint, allowing any network-reachable client to obtain a valid MCP session identifier without credentials. This enables unauthenticated enumeration and invocation of tools including `deepseek_sessions` and `deepseek_chat`, the latter of which can abuse the server-side `DEEPSEEK_API_KEY`.

MitigationDeploy version 1.8.0 or later, which contains the patch. For self-hosted HTTP mode, ensure an `authProvider` is configured or authentication middleware guards the `/mcp` endpoint, and avoid exposing port 3000 publicly.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
Low

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

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify installed DeepSeek MCP Server version
    Run 'npm list deepseek-mcp-server' or check package.json version field, or look for version in the server's startup output
    Affected if Version is 1.4.2, 1.5.0, 1.6.0, 1.7.0, 1.8.0, or any version between 1.4.2 and 1.8.0 inclusive
  2. Confirm self-hosted HTTP transport is enabled
    Check if the server is configured to run in HTTP mode (look for HTTP transport settings in config files, environment variables, or startup flags)
    Affected if HTTP transport mode is enabled and the server listens on an HTTP endpoint
  3. Verify authProvider is configured
    Examine the application code or configuration where createMcpExpressApp is called; look for an authProvider option being passed
    Affected if createMcpExpressApp is called WITHOUT an authProvider argument or the authProvider is set to null/undefined
  4. Check for authentication middleware on /mcp endpoint
    Inspect the server's middleware configuration or route definitions for the POST /mcp endpoint; verify that authentication middleware is applied to this route
    Affected if No authentication middleware protects the POST /mcp endpoint
  5. Confirm DEEPSEEK_API_KEY is present
    Check server environment variables or configuration for DEEPSEEK_API_KEY being set
    Affected if DEEPSEEK_API_KEY is defined in the server environment (this indicates the potential impact of key abuse)
  6. Assess network exposure of HTTP port
    Check if the HTTP service (typically on port 3000) is bound to a public IP or exposed to untrusted networks
    Affected if Port 3000 or the HTTP transport port is accessible from untrusted networks without firewall protection

A user is affected if they run DeepSeek MCP Server versions 1.4.2-1.8.0 with HTTP transport enabled, no authProvider configured, no middleware protecting /mcp, and the server is network-accessible.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Deploy version 1.8.0 or later, which contains the patch. For self-hosted HTTP mode, ensure an `authProvider` is configured or authentication middleware guards the `/mcp` endpoint, and avoid exposing port 3000 publicly.

Recommended fix High confidence

Version 1.8.0 or later of @arikusi/deepseek-mcp-server

  1. 1. Identify the currently deployed version of @arikusi/deepseek-mcp-server by checking package.json, Docker image tag, or running `npm list @arikusi/deepseek-mcp-server`
  2. 2. If the current version is between 1.4.2 (inclusive) and 1.8.0 (exclusive), upgrade to version 1.8.0 or later
  3. 3. For npm/yarn deployments: run `npm install @arikusi/deepseek-mcp-server@^1.8.0` or `yarn add @arikusi/deepseek-mcp-server@^1.8.0`
  4. 4. For Docker deployments: update the image tag in Dockerfile or docker-compose.yml to use version 1.8.0 or later (e.g., update the FROM or image reference)
  5. 5. Rebuild and restart the container/service
  6. 6. Verify the upgrade was successful by checking the installed version matches 1.8.0 or later
  7. 7. Test that authentication is now required for the /mcp endpoint
Caveat Minimal risk; the patch adds authentication to a previously unauthenticated endpoint, which is a security hardening change

Generated from the published advisory — verify against the referenced sources before acting.

Have this fixed Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing3.0 h
  • Review / QA2.0 h
11.0 hours of engineering $1,930
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-55605 in production — separate from our analysis above.

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  • Version or environment caveats, and links to real fixes
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