Vulnerability · Published Sep 18, 2026 · Assigned by GitHub_M
CVE-2026-59163Mnemosyne has JWT signature verification bypass sync server that allows authentication bypass
Critical 9.1
In plain English
A critical-severity security flaw in mnemosyne from AxDSan. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 26% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official 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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| PyPI | mnemosyne-memory | 3.10.1 | GHSA-xcw4-53cc-hv32 |
| PyPI | mnemosyne-memory | 3.10.1 | PYSEC-2026-4106 |
Affected products (as reported)
Weakness: CWE-347 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
References
- https://github.com/mnemosyne-oss/mnemosyne/security/advisories/GHSA-xcw4-53cc-hv32 x_refsource_CONFIRM
- https://github.com/mnemosyne-oss/mnemosyne/pull/373 x_refsource_MISC
- https://github.com/mnemosyne-oss/mnemosyne/commit/a0b6b8711a1a485304971710dc3571e29ff9dbeb x_refsource_MISC
- https://github.com/mnemosyne-oss/mnemosyne/releases/tag/v3.10.1 x_refsource_MISC