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TI-2026-18942 Aliases CVE-2026-23518GHSA-63m5-974w-448v

Fleet has a JWT signature bypass vulnerability in Azure AD MDM enrollment

Priority MEDIUM 48CWE-347Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Attack requirements
None
Impact type
Security bypass
Confidentiality · integrity · availability
High · High · High
Fix status
Fixed

Attack profile from CVSS 4.0 · CNA. Fix status from CNA and GitHub. Impact type from CWE-347.

Summary

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.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00254 17th percentileScored 2026-11-07
Fix Fixed fleet (fleetdm): 4.78.3, 4.77.1, 4.76.2 +2github.com/fleetdm/fleet (Go): 4.78.3, 4.77.1, 4.76.2 +2

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
Yes
Technical impact
Total

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
fleetdmfleet4.78.0 to before 4.78.3; 4.77.0 to before 4.77.1; 4.76.0 to before 4.76.2; 4.75.0 to before 4.75.2; before 4.53.34.78.3, 4.77.1, 4.76.2, 4.75.2, 4.53.3Patch availableCNA
—github.com/fleetdm/fleet (Go)4.78.0 to before 4.78.34.78.3Patch availableGHSA-63m5-974w-448v
—github.com/fleetdm/fleet (Go)4.77.0 to before 4.77.14.77.1Patch availableGHSA-63m5-974w-448v
—github.com/fleetdm/fleet (Go)4.76.0 to before 4.76.24.76.2Patch availableGHSA-63m5-974w-448v
—github.com/fleetdm/fleet (Go)4.75.0 to before 4.75.24.75.2Patch availableGHSA-63m5-974w-448v
—github.com/fleetdm/fleet (Go)before 4.43.5-0.20260112202845-e225ef57912c4.43.5-0.20260112202845-e225ef57912cPatch availableGHSA-63m5-974w-448v
  • fleet Vendorfleetdm Affected 4.78.0 to before 4.78.3; 4.77.0 to before 4.77.1; 4.76.0 to before 4.76.2; 4.75.0 to before 4.75.2; before 4.53.3 Fixed in 4.78.3, 4.77.1, 4.76.2, 4.75.2, 4.53.3 Patch available CNA
  • github.com/fleetdm/fleet (Go) Vendor— Affected 4.78.0 to before 4.78.3 Fixed in 4.78.3 Patch available GHSA-63m5-974w-448v
  • github.com/fleetdm/fleet (Go) Vendor— Affected 4.77.0 to before 4.77.1 Fixed in 4.77.1 Patch available GHSA-63m5-974w-448v
  • github.com/fleetdm/fleet (Go) Vendor— Affected 4.76.0 to before 4.76.2 Fixed in 4.76.2 Patch available GHSA-63m5-974w-448v
  • github.com/fleetdm/fleet (Go) Vendor— Affected 4.75.0 to before 4.75.2 Fixed in 4.75.2 Patch available GHSA-63m5-974w-448v
  • github.com/fleetdm/fleet (Go) Vendor— Affected before 4.43.5-0.20260112202845-e225ef57912c Fixed in 4.43.5-0.20260112202845-e225ef57912c Patch available GHSA-63m5-974w-448v

CPE configurations NVD · 2

CPEVersionsRoleVendor
cpe:2.3:a:fleetdm:fleet:*:*:*:*:*:*:*:*before 4.53.3; 4.75.0 to before 4.75.2; 4.76.0 to before 4.76.2; 4.78.0 to before 4.78.3Vulnerablefleetdm
cpe:2.3:a:fleetdm:fleet:4.77.0:*:*:*:*:*:*:*4.77.0Vulnerablefleetdm
  • cpe:2.3:a:fleetdm:fleet:*:*:*:*:*:*:*:* Versions before 4.53.3; 4.75.0 to before 4.75.2; 4.76.0 to before 4.76.2; 4.78.0 to before 4.78.3 Vulnerable ·fleetdm
  • cpe:2.3:a:fleetdm:fleet:4.77.0:*:*:*:*:*:*:* Versions 4.77.0 Vulnerable ·fleetdm

Remediation

  • Fix · CNA fleet (fleetdm) Fixed in 4.78.3, 4.77.1, 4.76.2, 4.75.2, 4.53.3
  • Fix · GHSA-63m5-974w-448v github.com/fleetdm/fleet (Go) Fixed in 4.78.3 Advisory →
  • Fix · GHSA-63m5-974w-448v github.com/fleetdm/fleet (Go) Fixed in 4.77.1 Advisory →
  • Fix · GHSA-63m5-974w-448v github.com/fleetdm/fleet (Go) Fixed in 4.76.2 Advisory →
  • Fix · GHSA-63m5-974w-448v github.com/fleetdm/fleet (Go) Fixed in 4.75.2 Advisory →
  • Fix · GHSA-63m5-974w-448v github.com/fleetdm/fleet (Go) Fixed in 4.43.5-0.20260112202845-e225ef57912c Advisory →

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-23518
  2. 2026-10-03 Alias added: GHSA-63m5-974w-448v

References

Patch 1

Advisory 2

Other 2

  • TI-2026-65639 Fleet before 4.87.0 Authentication Bypass via Device Identifiers CVSS 4.0CRITICAL 9.3
  • TI-2020-16097 SAML authentication vulnerability in Fleet CVSS 3.1CRITICAL 10.0
  • TI-2026-21066 Fleet server may terminate unexpectedly when handling certain gRPC requests CVSS 4.0HIGH 8.7
  • TI-2026-21065 Fleet's unbounded request body read allows remote Denial of Service CVSS 4.0HIGH 8.7
  • TI-2026-20084 Fleet Windows MDM Azure AD JWT Authentication Bypass CVSS 4.0HIGH 8.2
  • TI-2026-19339 Fleet has a rate limiting bypass via untrusted client IP headers CVSS 4.0MEDIUM 6.9
See all 31 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences