CVE-2026-55604

Name of the Vulnerable Software and Affected Versions DeepSeek MCP Server versions 1.4.2 through 1.6.x

Description The process-global SessionStore accepts caller-supplied session id values without binding them to an authenticated principal or transport session. This allows an attacker to enumerate active session IDs using the deepseek sessions tool and subsequently reuse a victim's session id in the deepseek chat tool to retrieve and continue the victim's conversation context. This issue is an Insecure Direct Object Reference (IDOR), which occurs when an application provides direct access to objects based on user-supplied input, leading to an authorization bypass.

Recommendations Update DeepSeek MCP Server to version 1.7.0.