CVE-2026-55604

HighCVSS 8.6

Published: 09/07/2026(UTC)Updated: 10/07/2026(UTC)Translated: 11/07/2026(UTC)NVD NIST

Exploitation Probability (EPSS)

Low risk

0.23%

13th percentile - higher than 13% of all known CVEs

Summary

A vulnerability in DeepSeek MCP Server allows an attacker to hijack user sessions by enumerating session IDs and reusing them in chat requests. The issue affects versions 1.4.2 through 1.7.0, where the global session store does not validate session ID authenticity.

Risk Assessment

An attacker can access the victim's conversation history, continue their chats, and potentially steal sensitive data processed within the chat session.

Recommendation

Immediately upgrade DeepSeek MCP Server to version 1.7.0 or later, which contains the fix for this vulnerability.

Other vulnerabilities in DeepSeek MCP Server

CVE-2026-55605Medium
A vulnerability in the DeepSeek MCP Server (versions 1.4.2 through 1.7.x) allows unauthenticated clients to access the HTTP POST /mcp endpoint. The lack of authentication enables session initialization, tool enumeration, and invocation of deepseek_sessions and deepseek_chat tools, potentially exposing the DeepSeek API key.

Original NVD description (English source)

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.