CVE-2026-23518
criticalpriority · track · 39EPSS 0.003 · 17 %ileEUUSEPSS · scored 2026-10-28
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
Technical severity, 0–10. One row per scoring source.
base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · high–critical · 8.1–9.8
ssvc
A stakeholder decision — act, attend, or track — from exploitation and impact.
weaknesses
The CWE weakness classes this flaw belongs to.
affected products (19)
Products and version ranges known to be affected.
- Go github.com/fleetdm/fleet< 4.43.5-0.20260112202845-e225ef57912cosvUSpkg:golang/github.com/fleetdm/fleet
advisories (2)
Vendor and ecosystem advisories describing this.
- GHSA-63m5-974w-448vFleet has a JWT signature bypass vulnerability in Azure AD MDM enrollment 2026-01-20ghsa · osvUS
### 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 [security@fleetdm.com](mailto:security@fleetdm.com) 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.
- GO-2026-4335Fleet has a JWT signature bypass vulnerability in Azure AD MDM enrollment in github.com/fleetdm/fleet2026-02-03vendor · osvUS
Fleet has a JWT signature bypass vulnerability in Azure AD MDM enrollment in github.com/fleetdm/fleet
also known as (5)
Other names and identifiers for this entity.
sources
Which sources assert this record, and when.
references (8)
External citations — patches, advisories, analysis.
- https://access.redhat.com/security/cve/cve-2026-23518cnnvd
- https://github.com/fleetdm/fleet/commit/e225ef57912c8f4ac8977e24b5ebe1d9fd875257cnnvd
- https://github.com/fleetdm/fleet/releasesPatchcnnvd
- https://github.com/fleetdm/fleet/security/advisories/GHSA-63m5-974w-448vcnnvd
- https://github.com/fleetdm/fleet/commit/e225ef57912c8f4ac8977e24b5ebe1d9fd875257enisa_euvd
- https://github.com/fleetdm/fleet/security/advisories/GHSA-63m5-974w-448venisa_euvd
- https://github.com/fleetdm/fleet/commit/e225ef57912c8f4ac8977e24b5ebe1d9fd875257Patchnvd
- https://github.com/fleetdm/fleet/security/advisories/GHSA-63m5-974w-448vVendor Advisorynvd
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