EUVD-2026-30374
GHSA-ffg9-j72f-j6xm
CVSS VectorNVD
CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Lifecycle Timeline
7DescriptionNVD
Summary
A vulnerability in Fleet's Windows MDM enrollment flow allows authentication tokens from any Azure AD tenant to be accepted. Because Fleet validates JWT signatures using Microsoft's multi-tenant JWKS endpoint but does not enforce the aud (audience) or iss (issuer) claims, any Microsoft-signed Azure AD access token containing the expected scopes can be used to authenticate to Fleet's MDM endpoints.
Impact
If Windows MDM is enabled, an attacker with access to any Azure AD tenant can obtain a valid Microsoft-signed token and use it to enroll unauthorized devices and interact with Fleet's MDM management APIs. During device management, Fleet may expose sensitive enrollment secrets embedded in MDM command payloads, enabling further unauthorized access.
Workarounds
If an immediate upgrade is not possible, affected Fleet users should temporarily disable Windows MDM.
For more information
If you have any questions or comments about this advisory: Email us at [security@fleetdm.com](mailto:security@fleetdm.com) Join #fleet in osquery Slack
Credits
We thank @zaddy6 for responsibly reporting this issue.
AnalysisAI
JWT authentication bypass in Fleet's Windows MDM enrollment allows attackers with access to any Azure AD tenant to enroll unauthorized devices and access management APIs. Fleet validates JWT signatures using Microsoft's multi-tenant JWKS endpoint but fails to verify 'aud' (audience) or 'iss' (issuer) claims, accepting any Microsoft-signed token with the expected scopes. …
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RemediationAI
Within 24 hours: Audit Azure AD tenants with access to Fleet enrollment endpoints and review device enrollment logs for anomalies. Within 7 days: Upgrade Fleet to version 4.82.0 or later. …
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