CVE-2026-59163 Details
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.
A vulnerability in the Mnemosyne sync server's authentication process allowed for JWT signature verification bypass. This issue was present in all versions through 3.10.0. The sync server accepted any well-formed JWT, including those with 'alg: none' or incorrectly signed, enabling an unauthenticated attacker to impersonate users and access or modify their synchronization data. The vulnerability arose because the server parsed JWTs using base64 decoding and then passed them to a library call that disabled signature verification. The flaw is critical for network-accessible sync servers, but less severe if the endpoint is only reachable via localhost.
Users should upgrade to Mnemosyne version 3.10.1, which includes a proper JWT signature verification implementation. For those unable to upgrade immediately, it is recommended to restrict network access to the sync server endpoint to trusted clients only.
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 Sep 18, 2026CISA-ADP
Assessed Sep 18, 2026References to Advisories, Solutions, and Tools
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| URL | Source(s) | Tag(s) |
|---|---|---|
| https://github.com/mnemosyne-oss/mnemosyne/security/advisories/GHSA-xcw4-53cc-hv32 | CISA-ADP | AdvisoryExploitRemedyVendor |
| https://github.com/mnemosyne-oss/mnemosyne/commit/a0b6b8711a1a485304971710dc3571e29ff9dbeb | [email protected] | Source CodeVendor |
| https://github.com/mnemosyne-oss/mnemosyne/pull/373 | [email protected] | Issue TrackingVendor |
| https://github.com/mnemosyne-oss/mnemosyne/releases/tag/v3.10.1 | [email protected] | Release NotesVendor |
| https://github.com/mnemosyne-oss/mnemosyne/security/advisories/GHSA-xcw4-53cc-hv32 | [email protected] | AdvisoryExploitRemedyVendor |
Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-347 | Improper Verification of Cryptographic Signature | [email protected] |
Affected Products
| Product | Versions |
|---|---|
| Mnemosyne | <= 3.10.0 (semver) |
CPE
Remediation
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Change History
2 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Sep 18, 2026 | New CVE Received | [email protected] |
| Sep 18, 2026 | CVE Modified | CISA-ADP |