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CVE-2026-22808 — Vulnerability in github.com/fleetdm/fleet — CVE...

MEDIUM

Fleet Windows MDM endpoint has a Cross-site Scripting vulnerability

Published January 20, 2026Updated February 3, 2026Source: osv

Summary

### Summary A cross-site scripting (XSS) vulnerability in Fleet’s Windows MDM authentication flow could allow an attacker to compromise a Fleet user account. In certain cases, this could lead to administrative access and the ability to perform privileged actions on managed devices. ### Impact If Windows MDM is enabled, an attacker could exploit a cross-site scripting (XSS) vulnerability by convincing an authenticated Fleet user to visit a malicious link. Successful exploitation could allow retrieval of the user’s Fleet authentication token from their browser. A compromised authentication token may grant administrative access to the Fleet API, allowing an attacker to perform privileged actions such as deploying scripts to managed hosts. This issue does not allow unauthenticated access and does not affect instances where Windows MDM is disabled. ### Patches - 4.78.2 - 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.

Advisory Timeline

  • First published January 20, 2026 (265 days ago).
  • Last revised February 3, 2026 — 14 days after initial publication.

Remediation

Upgrade to the fixed version using your package manager.

Go
Update github.com/fleetdm/fleet to 4.78.2 or later
go get github.com/fleetdm/fleet@v4.78.2
Go
Update github.com/fleetdm/fleet to 4.77.1 or later
go get github.com/fleetdm/fleet@v4.77.1
Go
Update github.com/fleetdm/fleet to 4.76.2 or later
go get github.com/fleetdm/fleet@v4.76.2
Go
Update github.com/fleetdm/fleet to 4.75.2 or later
go get github.com/fleetdm/fleet@v4.75.2
Go
Update github.com/fleetdm/fleet/v4 to 4.43.5-0.20260111020427-0e6c790803d1 or later
go get github.com/fleetdm/fleet/v4@v4.43.5-0.20260111020427-0e6c790803d1

After upgrading, run your dependency scanner again to confirm the vulnerability is resolved.

Affected Packages (5)

Affects 1 ecosystem: go (2).

PackageEcosystemAffectedFixed In
github.com/fleetdm/fleet
go
All versions4.78.2
github.com/fleetdm/fleet
go
All versions4.77.1
github.com/fleetdm/fleet
go
All versions4.76.2
github.com/fleetdm/fleet
go
All versions4.75.2
github.com/fleetdm/fleet/v4
go
All versions4.43.5-0.20260111020427-0e6c790803d1

Vulnerability Classification

Common Weakness Enumeration (CWE) identifiers for this vulnerability type.

  • CWE-79
    Cross-site Scripting (XSS)MITRE

CVSS Score Breakdown

What the CVSS (Common Vulnerability Scoring System) 8.7 score means for each attack dimension.

Attack Vector
Network
Attack Complexity
Low
Privileges Required
Low
User Interaction
P
Scope
—
Confidentiality
—
Integrity
—
Availability
—

CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:P/VC:N/VI:N/VA:N/SC:H/SI:H/SA:H

Frequently Asked Questions

What is CVE-2026-22808?
Fleet Windows MDM endpoint has a Cross-site Scripting vulnerability This vulnerability has been assigned a severity rating of MEDIUM (CVSS score: 8.7/10).
How do I check if my project is affected by CVE-2026-22808?
CVE-2026-22808 affects github.com/fleetdm/fleet and github.com/fleetdm/fleet/v4. Use GeekWala's free vulnerability scanner to check your dependencies against CVE-2026-22808 and 200,000+ other known vulnerabilities.

Severity & Exploitability

CVSS Score
8.7

High exploitability or significant impact. Prioritize remediation within days.

Also Known As

GHSA-gfpw-jgvr-cw4j
GO-2026-4336

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