@arikusi/deepseek-mcp-server has an Authorization Bypass Through User-Controlled Key

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

8.6 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:L

EPSS

• CVE-2026-55604: 0.37% estimated exploitation activity in the next 30 days; percentile 31.25 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Cross-Session Data Exposure via Caller-Controlled sessionid Project / Repository: arikusi/deepseek-mcp-server Affected version / commit tested: 1.6.0 / 04f28be2c6e99d3d4e443a6ae37cc35f0a71554a Vulnerability type: Authorization bypass / cross-session data exposure Authentication required: No Summary The process-global SessionStore accepts caller-supplied sessionid values without binding them to any authenticated principal or transport session. An attacker can enumerate active session IDs via deepseeksessions, then reuse a victim-controlled sessionid in deepseekchat to retrieve and continue the victim's conversation context. Affected Code - src/session.ts:42 - caller-controlled session IDs are looked up directly from the global in-memory map. - src/session.ts:67 - a new session is stored under the caller-controlled ID without ownership binding. - src/session.ts:109 - getMessages() retrieves messages for any supplied session ID. - src/tools/deepseek-chat.ts:195 - deepseekchat creates or…

Published by the source

25 Aug 2026, 18:37 UTC

Last modified by the source

25 Aug 2026, 18:37 UTC

Source last checked

26 Oct 2026, 13:01 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-fh3r-g96v-f578

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# Patch Next advisory brief: CVE-2026-55604

Advisory: @arikusi/deepseek-mcp-server has an Authorization Bypass Through User-Controlled Key
IDs: CVE-2026-55604, GHSA-fh3r-g96v-f578
Record: https://patchnext.com/advisories/cve-2026-55604 (revision 1, source checked 26 Oct 2026, 13:01 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.6)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: @arikusi/deepseek-mcp-server 1.7.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm @arikusi/deepseek-mcp-server: affected >= 1.4.2, < 1.7.0; fixed in 1.7.0

## Suggested inspection (read-only)
- `npm ls @arikusi/deepseek-mcp-server --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on @arikusi/deepseek-mcp-server.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-fh3r-g96v-f578 (GitHub-reviewed advisory GHSA-fh3r-g96v-f578 lists affected ranges: npm @arikusi/deepseek-mcp-server >=1.4.2 <1.7.0)

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