PT-2026-3741 · Go · Github.Com/Fleetdm/Fleet

Published 2026-01-20 · Updated 2026-01-20

OSV

CVSS v4.0

9.3

Critical

Base vector

AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

Summary

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.

Impact

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.

Patches

• 4.78.3
• 4.77.1
• 4.76.2
• 4.75.2
• 4.53.3

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 [e-mail] Join #fleet in [osquery Slack](https://join.slack.com/t/osquery/shared invite/zt-h29zm0gk-s2DBtGUTW4CFel0f0IjTEw)

Credits

We thank @secfox-ai for responsibly reporting this issue.

Fix

Improper Verification of Cryptographic Signature

Weakness Enumeration

CWE-347

Related Identifiers

GHSA-63M5-974W-448V

Affected Products

Github.Com/Fleetdm/Fleet

References · 6

• https://osv.dev/vulnerability/GHSA-63m5-974w-448v · Vendor Advisory
• https://nvd.nist.gov/vuln/detail/CVE-2026-23518 · Security Note
• https://github.com/fleetdm/fleet · Note
• https://github.com/fleetdm/fleet/security/advisories/GHSA-63m5-974w-448v · Note
• https://github.com/fleetdm/fleet/commit/e225ef57912c8f4ac8977e24b5ebe1d9fd875257 · Note
• https://pkg.go.dev/vuln/GO-2026-4335 · Note