CVE-2026-55604 Details
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.
A vulnerability exists in DeepSeek MCP Server versions 1.4.2 prior to 1.7.0, allowing for cross-session data exposure. The issue arises because the process-global 'SessionStore' accepts user-supplied 'session_id' values without linking them to any authenticated user or transport session. This flaw enables an attacker to enumerate active session IDs and, by reusing a victim's 'session_id', access and manipulate the victim's conversation context. The vulnerability is present in the HTTP transport mode, where all clients share the same session store, unlike the STDIO transport mode, where each client operates in its own server process.
Users should upgrade to DeepSeek MCP Server version 1.7.0 or later. For those using HTTP transport, it is recommended to upgrade immediately and adjust any client behavior that relied on the previous cross-client session sharing, as this feature has been removed. Users on STDIO transport do not need to take any action beyond upgrading.
Metrics
CVSS 4.0 Severity and Vector Strings:
VolerionCVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
Volerion
Assessed Jul 9, 2026CISA-ADP
Assessed Jul 10, 2026References to Advisories, Solutions, and Tools
By selecting these links, you will be leaving this site. These are references gathered from the official CVE record and are not endorsed by Volerion.
| URL | Source(s) | Tag(s) |
|---|---|---|
| https://github.com/arikusi/deepseek-mcp-server/security/advisories/GHSA-fh3r-g96v-f578 | CISA-ADP | AdvisoryExploitRemedyVendor |
| https://github.com/arikusi/deepseek-mcp-server/releases/tag/v1.7.0 | [email protected] | Release NotesVendor |
| https://github.com/arikusi/deepseek-mcp-server/security/advisories/GHSA-fh3r-g96v-f578 | [email protected] | AdvisoryExploitRemedyVendor |
Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-639 | Authorization Bypass Through User-Controlled Key | [email protected] |
Affected Products
| Product | Versions |
|---|---|
| Arikusi DeepSeek MCP Server | >= 1.4.2, < 1.7.0 (semver) |
CPE
Remediation
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Change History
2 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Jul 10, 2026 | CVE Modified | CISA-ADP |
| Jul 9, 2026 | New CVE Received | [email protected] |