If Windows MDM is enabled, an attacker can enroll rogue devices by submitting a forged JWT containing arbitrary identity claims. Due to missing JWT signature verification, Fleet accepts these claims without validating that the token was issued by Azure AD, allowing enrollment under any Azure AD user identity.
If an immediate upgrade is not possible, affected Fleet users should temporarily disable Windows MDM.
If you have any questions or comments about this advisory:
Email us at security@fleetdm.com Join #fleet in osquery Slack
{
"github_reviewed": true,
"github_reviewed_at": "2026-01-20T20:55:17Z",
"severity": "CRITICAL",
"nvd_published_at": null,
"cwe_ids": [
"CWE-347"
]
}