arikusi deepseek-mcp-server up to 1.7.x HTTP Transport README.md createMcpExpressApp improper authorization

Summaryinfo

A vulnerability described as critical has been identified in arikusi deepseek-mcp-server up to 1.7.x. This issue affects the function createMcpExpressApp of the file README.md of the component HTTP Transport. Executing a manipulation can lead to improper authorization. This vulnerability is handled as CVE-2026-55605. The attack can be executed remotely. There is not any exploit available.

Detailsinfo

A vulnerability classified as critical was found in arikusi deepseek-mcp-server up to 1.7.x. This vulnerability affects the function createMcpExpressApp of the file README.md of the component HTTP Transport. The manipulation with an unknown input leads to a improper authorization vulnerability. The CWE definition for the vulnerability is CWE-285. The product does not perform or incorrectly performs an authorization check when an actor attempts to access a resource or perform an action. As an impact it is known to affect confidentiality, integrity, and availability. CVE summarizes:

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.

The advisory is available at github.com. This vulnerability was named CVE-2026-55605 since 06/17/2026. The exploitation appears to be easy. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. Technical details are known, but there is no available exploit. This vulnerability is assigned to T1548.002 by the MITRE ATT&CK project.

Upgrading to version 1.8.0 eliminates this vulnerability.

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Productinfo

Type

• Artificial Intelligence Software

Vendor

• arikusi

Name

• deepseek-mcp-server

Version

• 1.0
• 1.1
• 1.2
• 1.3
• 1.4
• 1.5
• 1.6
• 1.7

Website

• Product: https://github.com/arikusi/deepseek-mcp-server/

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