CVE-2026-55604 arikusi CVE debrief

Who should care

Users of DeepSeek MCP Server, especially those using versions 1.4.2 to 1.6.0, should be aware of this vulnerability and take steps to mitigate it. This includes upgrading to version 1.7.0 or later and implementing additional authentication and session management mechanisms. Security teams and operators should review the vulnerability details and assess their exposure.

Technical summary

The process-global `SessionStore` in DeepSeek MCP Server 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. This vulnerability can lead to sensitive information disclosure if exploited.

Defensive priority

High

Recommended defensive actions

• Upgrade to version 1.7.0 or later
• Implement additional authentication and session management mechanisms
• Monitor for suspicious activity related to session enumeration and reuse
• Review compensating controls for exposed systems while remediation is scheduled and verified
• Check relevant monitoring, detection, and logs for exposed assets that need extra review
• Track exceptions, retest remediated assets, and close the item only after evidence is documented
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up

Evidence notes

The CVE record was published on 2026-07-09T22:17:06.247Z and was last modified on 2026-07-10T16:16:33.620Z. The NVD entry is currently 8.6 HIGH. The DeepSeek MCP Server vulnerability allows attackers to enumerate and reuse session IDs, potentially leading to sensitive information disclosure. Evidence is limited, and defenders should verify affected scope and vendor guidance.

Official resources