GHSA-63m5-974w-448v — fleet
Fix: fleetdm/fleet@e225ef5GHSA-63m5-974w-448v is a CWE-347 vulnerability in github.com/fleetdm/fleet. A fix is available for github.com/fleetdm/fleet — see the affected versions and patch details below.
Fleet has a JWT signature bypass vulnerability in Azure AD MDM enrollment
Exploitation Status
No confirmed exploitation observed yet
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- A successful exploit gives an attacker total control of the affected component, not partial access.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for GHSA-63m5-974w-448v.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
Real-World Exposure
github.com/fleetdm/fleet🐹github.com/fleetdm/fleet🐹github.com/fleetdm/fleet🐹github.com/fleetdm/fleet🐹github.com/fleetdm/fleetReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.
Description
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 [email protected] Join #fleet in osquery Slack
Credits
We thank @secfox-ai for responsibly reporting this issue.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/fleetdm/fleet | ≥ 4.78.0&&< 4.78.3 | 4.78.3go get github.com/fleetdm/fleet@v4.78.3 |
| 🐹Go | github.com/fleetdm/fleet | ≥ 4.77.0&&< 4.77.1 | 4.77.1go get github.com/fleetdm/fleet@v4.77.1 |
| 🐹Go | github.com/fleetdm/fleet | ≥ 4.76.0&&< 4.76.2 | 4.76.2go get github.com/fleetdm/fleet@v4.76.2 |
| 🐹Go | github.com/fleetdm/fleet | ≥ 4.75.0&&< 4.75.2 | 4.75.2go get github.com/fleetdm/fleet@v4.75.2 |
| 🐹Go | github.com/fleetdm/fleet | all versions | 4.43.5-0.20260112202845-e225ef57912cgo get github.com/fleetdm/fleet@v4.43.5-0.20260112202845-e225ef57912c |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/fleetdm/fleet, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update github.com/fleetdm/fleet to 4.78.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-63m5-974w-448v is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like GHSA-63m5-974w-448v can be triaged on real exposure rather than presence alone.
Tailored to GHSA-63m5-974w-448v. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-63m5-974w-448v in your dependencies?
O3 Security finds GHSA-63m5-974w-448v across Go dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.