Mnemosyne has JWT signature verification bypass sync server that allows authentication bypass

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-59163
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-18 18:17:07 UTC
Updated2026-09-18 18:17:07 UTC
DescriptionMnemosyne 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.

Risk And Classification

Primary CVSS: v3.1 9.1 CRITICAL from [email protected]

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

EPSS: 0.002510000 probability, percentile 0.168690000 (date 2026-09-21)

Problem Types: CWE-347 | CWE-347 CWE-347: Improper Verification of Cryptographic Signature

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary9.1CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
3.1CNADECLARED9.1CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
None

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

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA AxDSan Mnemosyne affected < 3.10.1 Not specified

References

ReferenceSourceLinkTags
github.com/mnemosyne-oss/mnemosyne/releases/tag/v3.10.1 [email protected] github.com
github.com/mnemosyne-oss/mnemosyne/security/advisories/GHSA-xcw4-53cc-hv32 134c704f-9b21-4f2e-91b3-4a467353bcc0 github.com
github.com/mnemosyne-oss/mnemosyne/commit/a0b6b8711a1a485304971710dc3571... [email protected] github.com
github.com/mnemosyne-oss/mnemosyne/pull/373 [email protected] github.com
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