What’s Vulnerable › Vulnerabilities

CVE-2026-55604: @arikusi/deepseek-mcp-server has an Authorization Bypass Through User-Controlled Key

• Severity: high (CVSS 8.6 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.4% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-07-09 · updated 2026-10-25
• Weakness: CWE-639

Description

DeepSeek MCP Server is an MCP server for DeepSeek V4. Starting in version 1.4.2 and prior to version 1.7.0, the process-global `SessionStore` accepts caller-supplied `session_id` values without binding them to any authenticated principal or transport session. An attacker can enumerate active session IDs via `deepseek_sessions`, then reuse a victim-controlled `session_id` in `deepseek_chat` to retrieve and continue the victim's conversation context. Version 1.7.0 contains a patch.

Affected products

• arikusi deepseek-mcp-server: from 1.4.2, < 1.7.0

References

• https://github.com/arikusi/deepseek-mcp-server/releases/tag/v1.7.0
• https://github.com/arikusi/deepseek-mcp-server/security/advisories/GHSA-fh3r-g96v-f578
• https://github.com/arikusi/deepseek-mcp-server/security/advisories/GHSA-fh3r-g96v-f578

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