CVE-2026-22808

Fleet Windows MDM endpoint has a Cross-site Scripting vulnerability

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.

Workarounds

If an immediate upgrade is not possible, affected Fleet users should temporarily disable Windows MDM.

For more information

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Credits

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

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.

Untrusted input is rendered as active markup in a victim's browser, which can run script in their session. Typical impact: session or credential theft, and actions taken as the user.

Kodem intelligence

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• 4.78.2
• 4.77.1
• 4.76.2
• 4.75.2
• 4.53.3

1. What is CVE-2026-22808? CVE-2026-22808 is a medium-severity cross-site scripting (XSS) vulnerability in github.com/fleetdm/fleet (go), affecting versions >= 4.78.0, < 4.78.2. It is fixed in 4.78.2, 4.77.1, 4.76.2, 4.75.2, 4.43.5-0.20260111020427-0e6c790803d1. Untrusted input is rendered as active markup in a victim's browser, which can run script in their session.
2. Which packages are affected by CVE-2026-22808?
   • github.com/fleetdm/fleet (go) (versions >= 4.78.0, < 4.78.2)
   • github.com/fleetdm/fleet/v4 (go) (versions < 4.43.5-0.20260111020427-0e6c790803d1)
3. Is there a fix for CVE-2026-22808? Yes. CVE-2026-22808 is fixed in 4.78.2, 4.77.1, 4.76.2, 4.75.2, 4.43.5-0.20260111020427-0e6c790803d1. Upgrade to this version or later.
4. Is CVE-2026-22808 exploitable, and should I be worried? Whether CVE-2026-22808 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
5. What actually determines whether CVE-2026-22808 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
6. How do I fix CVE-2026-22808?
   • Upgrade github.com/fleetdm/fleet to 4.78.2 or later
   • Upgrade github.com/fleetdm/fleet to 4.77.1 or later
   • Upgrade github.com/fleetdm/fleet to 4.76.2 or later
   • Upgrade github.com/fleetdm/fleet to 4.75.2 or later
   • Upgrade github.com/fleetdm/fleet/v4 to 4.43.5-0.20260111020427-0e6c790803d1 or later

Other vulnerabilities in github.com/fleetdm/fleet