Authentication Bypass in DeepSeek MCP Server Affecting Self-Hosted Deployments
CVE-2026-55605

5.3MEDIUM

Key Information:

Vendor

Arikusi

Status
Deepseek-mcp-server
Vendor
CVE Published:
9 July 2026

What is CVE-2026-55605?

The DeepSeek MCP Server version 1.4.2 to 1.7.9 contains a vulnerability that allows unauthenticated clients to access sensitive functionalities. Specifically, the self-hosted HTTP transport exposes a POST endpoint that lacks proper authentication, enabling attackers to initialize a session and interact with critical tools without credentials. In testing, it was demonstrated that an unauthenticated client could enumerate available tools and invoke functionalities such as deepseek_sessions and deepseek_chat, potentially exploiting the server-side API key. This vulnerability highlights significant security concerns for self-hosted deployments, especially since HTTP mode is enabled by default in containerized environments. It is crucial for users to upgrade to version 1.8.0 or later to mitigate this risk.

Affected Version(s)

deepseek-mcp-server >= 1.4.2, < 1.8.0

References

https://github.com/arikusi/deepseek-mcp-server/security/a...
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https://github.com/arikusi/deepseek-mcp-server/blob/main/...
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https://github.com/arikusi/deepseek-mcp-server/releases/t...
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CVSS V3.1

Score:
5.3
Severity:
MEDIUM
Confidentiality:
None
Integrity:
None
Availability:
None
Attack Vector:
Network
Attack Complexity:
Low
Privileges Required:
None
User Interaction:
None
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

.