← Vulnerability feed

Vulnerability record · CVE-2026-59163 · published 18 September 2026

CVE-2026-59163: Improper verification of cryptographic signature vulnerability

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.

9.1 CVSS 3.1 Critical EPSS 0.33% · top 77.0% CWE-347 · Improper verification of cryptographic signature Deferred
9.1CVSS 3.1 base score
0.33%EPSS exploitation probability, 30 days
NoNot in CISA KEV
0Affected product versions listed by NVD
5References
24 Sep 2026Last modified by NVD

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.

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

References

LinkTags
https://github.com/mnemosyne-oss/mnemosyne/commit/a0b6b8711a1a485304971710dc3571e29ff9dbeb
https://github.com/mnemosyne-oss/mnemosyne/pull/373
https://github.com/mnemosyne-oss/mnemosyne/releases/tag/v3.10.1
https://github.com/mnemosyne-oss/mnemosyne/security/advisories/GHSA-xcw4-53cc-hv32
https://github.com/mnemosyne-oss/mnemosyne/security/advisories/GHSA-xcw4-53cc-hv32

Track CVE-2026-59163 inside VULONE

Watch it alongside the ransomware crews, C2 infrastructure and forum chatter that reference it, query it through the API and pull it into your SIEM over TAXII.

Start free Open in platform

Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

10.0CVE-2026-5430Wso2 api control plane improper verification of cryptographic signature vulnerabilityThe JWT authentication mechanism accepts tokens signed with algorithms other than those explicitly configured or supported. This allows an attacker t…KEVEPSS 0.59%9.5CVE-2026-48558SimpleHelp OIDC authentication bypass via unverified token signatureSimpleHelp 5.5.15 and earlier and 6.0 pre-release versions accept OIDC identity tokens without verifying their cryptographic signature. When OIDC is …KEVEPSS 5.7%analysed9.8CVE-2025-59718Fortinet FortiOS/FortiProxy SAML signature check bypass in FortiCloud SSOFortiOS, FortiProxy and FortiSwitchManager fail to properly verify the cryptographic signature of SAML responses used for FortiCloud SSO login. An un…KEVEPSS 68%analysed4.6CVE-2025-47827IGEL OS Secure Boot bypass via improper signature verificationIGEL OS before version 11 fails to properly verify a cryptographic signature in the igel-flash-driver module, allowing Secure Boot to be bypassed. A …KEVEPSS 4.9%analysed10.0CVE-2020-2021PAN-OS SAML signature verification bypass allows authentication bypassPAN-OS fails to properly verify SAML signatures when SAML authentication is enabled and the 'Validate Identity Provider Certificate' option is unchec…KEVEPSS 4.4%analysed5.5CVE-2013-3900Windows WinVerifyTrust Authenticode signature verification RCECVE-2013-3900 is a remote code execution flaw in how the Windows WinVerifyTrust function verifies Authenticode signatures on portable executable file…KEVEPSS 45%analysed7.8CVE-2020-1464Windows file signature validation spoofing allows loading of improperly signed filesWindows incorrectly validates file signatures, so a crafted file can be treated as properly signed. This lets an attacker bypass the security feature…KEVEPSS 39%analysed

Source: NIST National Vulnerability Database (record CVE-2026-59163), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.