CVE-2026-59163

CRITICALPre-NVD 9.19.1—
EchelonGraph scoreMEDIUM confidence

This critical-severity CVE scores 9.1 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.3%, top 83% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, secondary
9.1EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 9.1Exploit: None knownExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

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 v3
9.1
EG Score
9.1(medium)
EG Risk
46(Track)
EG Risk 46/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity91% × 45%
Exploitation0% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
17%
KEV
Not listed

Published

September 18, 2026

Last Modified

September 18, 2026

Advisory Details (4)

Auto-updated Sep 18, 2026
Patch available. Sources: github_pr, github_commit, github_release, github.
github_release Patch Available

v3.10.1

Patch available: mnemosyne-oss/mnemosyne v3.10.1

https://github.com/mnemosyne-oss/mnemosyne/releases/tag/v3.10.1
github_commit Patch Available

commit a0b6b8711a1a (mnemosyne-oss/mnemosyne)

Patch available: mnemosyne-oss/mnemosyne v3.10.1 (contains commit a0b6b8711a1a)

https://github.com/mnemosyne-oss/mnemosyne/commit/a0b6b8711a1a485304971710dc3571e29ff9dbeb
github_pr Patch Available

chore: release: v3.10.1 — critical JWT signature verification fix (CVE GHSA-xcw4-53cc-hv32)

Patch available: mnemosyne-oss/mnemosyne v3.10.1 (PR #373 merged 2026-06-22)

https://github.com/mnemosyne-oss/mnemosyne/pull/373
github Patch Available

JWT signature verification bypass in Mnemosyne sync server allows authentication bypass · Advisory · mnemosyne-oss/mnemosyne · GitHub

https://github.com/mnemosyne-oss/mnemosyne/security/advisories/GHSA-xcw4-53cc-hv32

Vendor Advisories for CVE-2026-59163(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 4× in last 7d / 4× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-09-19 17:14 UTCEG score recompute
  2. 2026-09-18 18:27 UTCEG score recompute
  3. 2026-09-18 18:00 UTCEG score recompute
  4. 2026-09-18 17:59 UTCMITRE cvelistV5first tracked

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-59163?
CVE-2026-59163 is a critical vulnerability published on September 18, 2026. 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…
When was CVE-2026-59163 disclosed?
CVE-2026-59163 was first published in the National Vulnerability Database on September 18, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-59163 actively exploited?
CVE-2026-59163 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 83.1% of all scored CVEs.
What is the CVSS score of CVE-2026-59163?
CVE-2026-59163 has a CVSS v3 base score of 9.1 (NVD).
How do I remediate CVE-2026-59163?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-59163, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

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