CVE-2026-59163

CRITICALPre-NVD 9.19.1
EchelonGraph scoreMEDIUM confidence

“—” beside the score: it is equal to the CVSS score beside it.

Score 9.1 from GitHub Security Advisory (severity: CRITICAL) published 2026-09-18. A secondary CVSS source baseline 9.1; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: EPSS, GitHub Security Advisory, a secondary CVSS source
Elevated

Also known asEUVD-2026-83263 (ENISA EUVD) · GHSA-xcw4-53cc-hv32 (GitHub Security Advisories) · PYSEC-2026-4106 (OSV.dev)Source: ENISA EUVD

9.1EG
EchelonGraph verdictPlan a fixRemediate within your standard update timelines at low or medium mission impact and sooner than that at high (the SSVC decision on this page).
  • CISA's Vulnrichment rates exploitation as PoC; EchelonGraph holds no exploit-code reference for it
CISA-KEV: Not listedEPSS PROB: 0.3%CVSS: 9.1Exploit: No code on recordExposed services: Not assessed

A fix is available — apply it.

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
9.1CRITICALmedium confidence
EG Risk
72
EG Risk 72/100

EG Risk is EchelonGraph's 0–100 priority score. It fuses impact severity (EG Severity, the CVSS base score, never the KEV-floored or EPSS-lifted EG Score) with real-world exploitation and automatability, under weights EchelonGraph set by hand, so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner.

How it’s computed (value × EchelonGraph’s weight)
Severity91% × 45%
Impact severity (EG Severity): CVSS 9.1 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation40% × 40%
EchelonGraph's fixed weight for EG-KEV Tier 3 (Elevated): a constant, not a probability.
Automatability100% × 15%
CISA's SSVC Automatable value: yes (Vulnrichment).
SSVC (CISA's decision table, applied by EchelonGraph): Track at low, Track* at medium and Attend at high mission impact.
Exploitation public PoC (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.
Action: A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.
EPSS PROB
0.3%
EPSS %ILE
25th
KEV
Not listed

What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)

The EG score (9.1): severity, escalated by confirmed exploitation. This CVE's 9.1 is its impact severity (EG Severity), not escalated.

EG Severity
9.1 CRITICALCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
EG Likelihood
0.3% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-11-12). FIRST's exploitation probability, not an EchelonGraph model.
Confirmed exploitation
None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
EG Priority
SSVC Track* at medium mission impactTrack at low, Track* at medium and Attend at high mission impact.CISA BOD 26-04: 3 days if the affected system is publicly exposed; 60 days if it is not.Each input and its source, and whom BOD 26-04 binds: the SSVC and BOD 26-04 blocks below.

SSVC (CISA's decision table, applied by EchelonGraph)Track at low, Track* at medium and Attend at high mission impact.

A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.

Exploitation public PoC (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table

BOD 26-04 (CISA's remediation timeline, Table 1)3 days if the affected system is publicly exposed; 60 days if it is not.

The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable yes (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it

Published

September 18, 2026

Last Modified

September 24, 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 pull request 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 advisoryMentions a patch (unverified)

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.

Patch Availability(1)

Vendor / EcosystemFix (by version range) / PatchReleasedSource
pipmnemosyne-memory @ 3.10.1 (fixes <= 3.10.0)—ghsa

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Affected Packages

(1 across 1 ecosystem)
PyPI(1)
PackageVulnerable rangeFix by version rangeDependents
mnemosyne-memory1.10.1 ... 3.9.0 (25 versions)
  • every version up to 3.10.1: fixed in 3.10.1
—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 13× in last 7d / 44× in last 30d)

Each row is a time one of our pipelines fetched, updated or re-scored this CVE. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed its CVE.org record (CNA or CISA ADP). An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). "EchelonGraph re-scored" is our own recompute of this CVE's score, not an update from a source, and is not counted in the refreshes above. Most recent first.

Showing the most recent 100 of 129 rows on record for this CVE.

A repeat, a row identical to one the same pipeline wrote less than 10 seconds earlier, is not a separate refresh and is not counted. None are among the latest 100 rows. The 29 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-11-13 16:53 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  2. 2026-11-12 22:44 UTCEchelonGraph re-scored
  3. 2026-11-12 22:44 UTCGHSA enrichmentGHSA-xcw4-53cc-hv32 · GitHub severity CRITICAL · GitHub CVSS 9.1
  4. 2026-11-12 16:34 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  5. 2026-11-11 21:47 UTCEchelonGraph re-scored
  6. 2026-11-11 21:47 UTCGHSA enrichmentGHSA-xcw4-53cc-hv32 · GitHub severity CRITICAL · GitHub CVSS 9.1
  7. 2026-11-11 16:40 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  8. 2026-11-10 21:02 UTCEchelonGraph re-scored
  9. 2026-11-10 21:02 UTCGHSA enrichmentGHSA-xcw4-53cc-hv32 · GitHub severity CRITICAL · GitHub CVSS 9.1
  10. 2026-11-10 16:44 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  11. 2026-11-09 20:02 UTCEchelonGraph re-scored
  12. 2026-11-09 20:02 UTCGHSA enrichmentGHSA-xcw4-53cc-hv32 · GitHub severity CRITICAL · GitHub CVSS 9.1
  13. 2026-11-09 16:35 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  14. 2026-11-08 19:17 UTCEchelonGraph re-scored
  15. 2026-11-08 19:17 UTCGHSA enrichmentGHSA-xcw4-53cc-hv32 · GitHub severity CRITICAL · GitHub CVSS 9.1
  16. 2026-11-08 16:40 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  17. 2026-11-07 18:32 UTCEchelonGraph re-scored
  18. 2026-11-07 18:32 UTCGHSA enrichmentGHSA-xcw4-53cc-hv32 · GitHub severity CRITICAL · GitHub CVSS 9.1
  19. 2026-11-07 16:39 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  20. 2026-11-06 17:48 UTCEchelonGraph re-scored
  21. 2026-11-06 17:48 UTCGHSA enrichmentGHSA-xcw4-53cc-hv32 · GitHub severity CRITICAL · GitHub CVSS 9.1
  22. 2026-11-06 16:38 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  23. 2026-11-06 13:25 UTCOSV refresh
  24. 2026-11-05 17:04 UTCEchelonGraph re-scored
  25. 2026-11-05 17:04 UTCGHSA enrichmentGHSA-xcw4-53cc-hv32 · GitHub severity CRITICAL · GitHub CVSS 9.1
Show 75 more
  1. 2026-11-05 16:38 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  2. 2026-11-04 16:36 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  3. 2026-11-04 16:19 UTCEchelonGraph re-scored
  4. 2026-11-04 16:19 UTCGHSA enrichmentGHSA-xcw4-53cc-hv32 · GitHub severity CRITICAL · GitHub CVSS 9.1
  5. 2026-11-03 16:48 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  6. 2026-11-03 15:34 UTCEchelonGraph re-scored
  7. 2026-11-03 15:34 UTCGHSA enrichmentGHSA-xcw4-53cc-hv32 · GitHub severity CRITICAL · GitHub CVSS 9.1
  8. 2026-11-02 16:45 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  9. 2026-11-02 14:50 UTCEchelonGraph re-scored
  10. 2026-11-02 14:50 UTCGHSA enrichmentGHSA-xcw4-53cc-hv32 · GitHub severity CRITICAL · GitHub CVSS 9.1
  11. 2026-11-01 16:35 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  12. 2026-11-01 14:05 UTCGHSA enrichmentGHSA-xcw4-53cc-hv32 · GitHub severity CRITICAL · GitHub CVSS 9.1
  13. 2026-11-01 07:42 UTCGHSA enrichmentGHSA-xcw4-53cc-hv32 · GitHub severity CRITICAL · GitHub CVSS 9.1
  14. 2026-11-01 07:42 UTCEchelonGraph re-scored
  15. 2026-10-31 16:33 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  16. 2026-10-31 13:20 UTCEchelonGraph re-scored
  17. 2026-10-30 16:34 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  18. 2026-10-30 12:35 UTCEchelonGraph re-scored
  19. 2026-10-29 16:33 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  20. 2026-10-29 11:47 UTCEchelonGraph re-scored
  21. 2026-10-28 16:32 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  22. 2026-10-28 11:02 UTCEchelonGraph re-scored
  23. 2026-10-27 16:32 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  24. 2026-10-27 09:27 UTCEchelonGraph re-scored
  25. 2026-10-26 16:31 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  26. 2026-10-26 08:38 UTCEchelonGraph re-scored
  27. 2026-10-25 16:33 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  28. 2026-10-25 14:16 UTCEchelonGraph re-scored
  29. 2026-10-25 07:54 UTCEchelonGraph re-scored
  30. 2026-10-24 16:33 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  31. 2026-10-24 07:09 UTCEchelonGraph re-scored
  32. 2026-10-23 16:32 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  33. 2026-10-23 06:25 UTCEchelonGraph re-scored
  34. 2026-10-22 16:34 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  35. 2026-10-22 05:40 UTCEchelonGraph re-scored
  36. 2026-10-21 16:33 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  37. 2026-10-21 04:55 UTCEchelonGraph re-scored
  38. 2026-10-20 16:33 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  39. 2026-10-20 04:11 UTCEchelonGraph re-scored
  40. 2026-10-19 16:32 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  41. 2026-10-19 03:20 UTCEchelonGraph re-scored
  42. 2026-10-18 16:32 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
  43. 2026-10-18 03:27 UTCEchelonGraph re-scored
  44. 2026-10-18 02:35 UTCEchelonGraph re-scored
  45. 2026-10-17 16:35 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
  46. 2026-10-17 01:51 UTCEchelonGraph re-scored
  47. 2026-10-16 16:43 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
  48. 2026-10-16 01:06 UTCEchelonGraph re-scored
  49. 2026-10-15 16:32 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
  50. 2026-10-14 20:08 UTCEchelonGraph re-scored
  51. 2026-10-14 16:33 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
  52. 2026-10-13 16:34 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
  53. 2026-10-13 16:16 UTCEchelonGraph re-scored
  54. 2026-10-12 16:34 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
  55. 2026-10-12 15:32 UTCEchelonGraph re-scored
  56. 2026-10-11 19:36 UTCEchelonGraph re-scored
  57. 2026-10-11 16:51 UTCEchelonGraph re-scored
  58. 2026-10-11 14:14 UTCEchelonGraph re-scored
  59. 2026-10-11 13:49 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
  60. 2026-10-11 11:23 UTCEchelonGraph re-scored
  61. 2026-10-10 23:20 UTCEchelonGraph re-scored
  62. 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
  63. 2026-10-09 20:40 UTCEchelonGraph re-scored
  64. 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
  65. 2026-10-08 17:25 UTCEchelonGraph re-scored
  66. 2026-10-08 17:13 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
  67. 2026-10-08 01:44 UTCEchelonGraph re-scored
  68. 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
  69. 2026-10-06 18:44 UTCEchelonGraph re-scored
  70. 2026-10-06 15:18 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
  71. 2026-10-05 19:57 UTCEchelonGraph re-scored
  72. 2026-10-05 17:43 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
  73. 2026-10-05 01:04 UTCEchelonGraph re-scored
  74. 2026-10-04 23:22 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
  75. 2026-10-03 14:46 UTCEchelonGraph re-scored

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Frequently asked(5)

What is CVE-2026-59163?
CVE-2026-59163 is a critical-severity vulnerability; its CVE record was 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 the CVE record for CVE-2026-59163 published?
The CVE record for CVE-2026-59163 was published on September 18, 2026. That is the record's publication date; the vulnerability itself may have been made public earlier. EchelonGraph's copy of the record carries a last-modified date of September 24, 2026; the record at its source may have been updated since.
Is CVE-2026-59163 actively exploited?
CVE-2026-59163 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.3% probability of exploitation in the next 30 days (25th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-59163?
CVE-2026-59163 has a CVSS base score of 9.1 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-59163?
A fix for CVE-2026-59163 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-59163 are linked in the Vendor Advisories panel on this page.

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