CVE-2026-23518

CRITICALNVD 9.89.8—
EchelonGraph scoreMEDIUM confidence

This critical-severity CVE scores 9.8 under NVD CVSS v3. EPSS exploit probability: 0.2%, top 87% 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, nvd
9.8
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 0%CVSS: 9.8Exploit: NoneExposed: 0

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

Fleet is open source device management software. In versions prior to 4.78.3, 4.77.1, 4.76.2, 4.75.2, and 4.53.3, a vulnerability in Fleet's Windows MDM enrollment flow could allow an attacker to submit forged authentication tokens that are not properly validated. Because JWT signatures were not verified, Fleet could accept attacker-controlled identity claims, enabling enrollment of unauthorized devices under arbitrary Azure AD user identities. Versions 4.78.3, 4.77.1, 4.76.2, 4.75.2, and 4.53.3 fix the issue. If an immediate upgrade is not possible, affected Fleet users should temporarily disable Windows MDM.

CVSS v3
9.8
EG Score
9.8(medium)
EG Risk
59(Track)
EG Risk 59/100SSVC: 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
Severity98% × 45%
Exploitation0% × 40%
Automatability100% × 15%
Action: Routine — remediate on your standard cadence.
EPSS
13.4%
KEV
Not listed

Published

January 21, 2026

Last Modified

February 27, 2026

Advisory Details (2)

Auto-updated Jun 2, 2026
Patch available. Sources: github_commit, github.
github Patch Available

JWT signature bypass vulnerability in Azure AD MDM enrollment · Advisory · fleetdm/fleet · GitHub

https://github.com/fleetdm/fleet/security/advisories/GHSA-63m5-974w-448v
github_commit

commit e225ef57912c (fleetdm/fleet)

Fix landed in fleetdm/fleet commit e225ef57912c — awaiting tagged release

https://github.com/fleetdm/fleet/commit/e225ef57912c8f4ac8977e24b5ebe1d9fd875257

Affected Packages

(2 across 1 ecosystem)
Go(2)
PackageVulnerable rangeFixed inDependents
github.com/fleetdm/fleet—4.43.5-0.20260112202845-e225ef57912c—
github.com/fleetdm/fleet/v4—4.78.3—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 13× in last 7d / 52× 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. 2026-07-23 03:07 UTCEG score recompute
  2. 2026-07-22 14:08 UTCEPSS rescore
  3. 2026-07-21 15:24 UTCEPSS rescore
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  5. 2026-07-20 17:08 UTCEPSS rescore
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  19. 2026-07-13 21:07 UTCOSV refresh
  20. 2026-07-13 06:13 UTCEPSS rescore
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  1. 2026-07-08 15:15 UTCEPSS rescore
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  3. 2026-07-07 13:46 UTCEPSS rescore
  4. 2026-07-06 16:27 UTCEPSS rescore
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  18. 2026-06-28 04:56 UTCEPSS rescore
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  20. 2026-06-27 03:08 UTCEPSS rescore
  21. 2026-06-25 18:46 UTCOSV refresh
  22. 2026-06-25 13:49 UTCEPSS rescore
  23. 2026-06-25 13:49 UTCEPSS rescore
  24. 2026-06-24 14:05 UTCEPSS rescore
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  26. 2026-06-23 21:33 UTCEPSS rescore
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  28. 2026-06-22 14:25 UTCEPSS rescore
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  30. 2026-06-21 14:56 UTCEPSS rescore
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  40. 2026-06-15 17:48 UTCEPSS rescore
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  48. 2026-06-10 13:22 UTCEPSS rescore
  49. 2026-06-08 14:17 UTCEPSS rescore
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  51. 2026-06-07 15:25 UTCEPSS rescore
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  53. 2026-06-06 13:47 UTCEPSS rescore
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  56. 2026-06-05 22:47 UTCEPSS rescore
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  67. 2026-05-31 22:30 UTCEPSS rescore
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  69. 2026-05-31 00:16 UTCEPSS rescore
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  71. 2026-05-31 00:16 UTCEPSS rescore
  72. 2026-05-29 15:29 UTCEG score recompute
  73. 2026-05-29 13:44 UTCEPSS rescore
  74. 2026-05-29 13:44 UTCEPSS rescore

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-23518?
CVE-2026-23518 is a critical vulnerability published on January 21, 2026. Fleet is open source device management software. In versions prior to 4.78.3, 4.77.1, 4.76.2, 4.75.2, and 4.53.3, a vulnerability in Fleet's Windows MDM enrollment flow could allow an attacker to submit forged authentication tokens that are not properly validated. Because JWT signatures were not…
When was CVE-2026-23518 disclosed?
CVE-2026-23518 was first published in the National Vulnerability Database on January 21, 2026, with the most recent update on February 27, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-23518 actively exploited?
CVE-2026-23518 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 13.4% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-23518?
CVE-2026-23518 has a CVSS v3 base score of 9.8 (NVD).
How do I remediate CVE-2026-23518?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-23518, 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.

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