CVE-2026-59163 Mnemosyne has JWT signature verification bypass sync server that allows authentication bypass
Attackers can bypass authentication in Mnemosyne's sync server by submitting unsigned or incorrectly signed JWTs, gaining unauthorized access.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-59163?
CVE-2026-59163 is a critical authentication bypass vulnerability in AxDSan mnemosyne, published on 18 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
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.
Weakness: CWE-347
Which versions are affected by CVE-2026-59163?
3 open source packages ship an affected version, including mnemosyne-memory.
| Package | Affected | Fixed in |
|---|---|---|
mnemosyne-memory PyPI | All versions | 3.10.1 |
mnemosyne-memory PyPI | All versions | 3.10.1 |
mnemosyne-memory PyPI | All versions | 3.10.1 |
How do I fix CVE-2026-59163?
Upgrade mnemosyne-memory to 3.10.1 or later.
Upgrade, and rotate credentials and sessions that may have been exposed. More about Authentication bypass.
Is CVE-2026-59163 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-59163 exists.
Sources
Also known as GHSA-xcw4-53cc-hv32, PYSEC-2026-4106.