Mnemosyne is a memory layer for artificial intelligence agents. Prior to v3.10.1, the auth check in mnemosyne/core/sync_server.py parsed the JWT's header and payload using base64 decoding, then passed the token to a jwt library call with options that effectively disabled signature verification. The server accepted any well-formed token regardless of the signature, including tokens with alg: none and tokens signed with the wrong key. The fix in v3.10.1 replaces the broken decode with a from-scratch HS256 verifier using only the Python standard library. For users who cannot upgrade immediately, restrict network access to the sync server endpoint to trusted clients only. Firewall, reverse proxy with mTLS, or localhost bind with SSH tunnel are all viable. The vulnerability is not exploitable against an unreachable endpoint.

Project Subscriptions

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Advisories
Source ID Title
Github GHSA Github GHSA GHSA-xcw4-53cc-hv32 Mnemosyne has JWT signature verification bypass sync server that allows authentication bypass
Fixes

Solution

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Workaround

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History

Fri, 18 Sep 2026 21:30:00 +0000

Type Values Removed Values Added
Description Mnemosyne is a memory layer for artificial intelligence agents. Prior to v3.10.1, the auth check in mnemosyne/core/sync_server.py parsed the JWT's header and payload using base64 decoding, then passed the token to a jwt library call with options that effectively disabled signature verification. The server accepted any well-formed token regardless of the signature, including tokens with alg: none and tokens signed with the wrong key. The fix in v3.10.1 replaces the broken decode with a from-scratch HS256 verifier using only the Python standard library. For users who cannot upgrade immediately, restrict network access to the sync server endpoint to trusted clients only. Firewall, reverse proxy with mTLS, or localhost bind with SSH tunnel are all viable. The vulnerability is not exploitable against an unreachable endpoint.
Title Mnemosyne has JWT signature verification bypass sync server that allows authentication bypass
Weaknesses CWE-347
References
Metrics cvssV3_1

{'score': 9.1, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N'}

ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'poc', 'Technical Impact': 'total'}, 'version': '2.0.3'}


Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-09-18T18:01:56.013Z

Reserved: 2026-07-02T16:50:27.887Z

Link: CVE-2026-59163

cve-icon Vulnrichment

Updated: 2026-09-18T18:01:49.553Z

cve-icon NVD

Status : Received

Published: 2026-09-18T18:17:07.807

Modified: 2026-09-18T18:17:07.807

Link: CVE-2026-59163

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-09-19T12:00:08Z

Weaknesses