How severe is CVE-2026-22808?

No CVSS score has been assigned to CVE-2026-22808 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by CVE-2026-22808?

CVE-2026-22808 affects the following packages: github.com/fleetdm/fleet (Go), github.com/fleetdm/fleet (Go), github.com/fleetdm/fleet (Go), github.com/fleetdm/fleet (Go), github.com/fleetdm/fleet/v4 (Go). Ecosystems affected: Go.

How do I fix CVE-2026-22808?

Update github.com/fleetdm/fleet to 4.78.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-22808 is resolved across your whole dependency graph.

How do I detect CVE-2026-22808 in my Go dependencies?

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.

How do I mitigate CVE-2026-22808 if there is no patch (or I can't update yet)?

Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page.

Is CVE-2026-22808 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-22808 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2026-22808?

CVE-2026-22808 has an EPSS (Exploit Prediction Scoring System) score of 0.2%, placing it in the 16th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2026-22808?

CVE-2026-22808 is classified as Cross-site Scripting (XSS) (CWE-79). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation. This is a high-impact weakness class that often enables remote code execution or data exposure.

When was CVE-2026-22808 published, and has it been updated?

CVE-2026-22808 was published on January 21, 2026 and was last updated on October 28, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐹 Go

Not in CISA KEV

CVE-2026-22808 — fleet

Fix: fleetdm/fleet@0e6c790

CVE-2026-22808 is a Cross-site Scripting (XSS) vulnerability in github.com/fleetdm/fleet. A fix is available for github.com/fleetdm/fleet — see the affected versions and patch details below.

Fleet Windows MDM endpoint has a Cross-site Scripting vulnerability

Also known asGHSA-gfpw-jgvr-cw4jGO-2026-4336

Published

Jan 21, 2026

Updated

Oct 28, 2026

Affected

5 pkgs

Patched

5 / 5

Exploits

None indexed

Exploitation data as of Nov 7, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

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 CVE-2026-22808.

EPSS Exploitation Probability

via FIRST.org ↗

0.2%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs16th percentile — riskier than 16% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

Real-World Exposure

5 pkgs affected

🐹github.com/fleetdm/fleet🐹github.com/fleetdm/fleet🐹github.com/fleetdm/fleet🐹github.com/fleetdm/fleet🐹github.com/fleetdm/fleet/v4

Real-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 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 [email protected] Join #fleet in osquery Slack

Credits

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

Affected Packages

5 total 5 fixed

Ecosystem	Package	Vulnerable range	Fix
🐹Go	`github.com/fleetdm/fleet`	≥ 4.78.0&&< 4.78.2	4.78.2`go get github.com/fleetdm/fleet@v4.78.2`
🐹Go	`github.com/fleetdm/fleet`	≥ 4.77.0&&< 4.77.1	4.77.1`go get github.com/fleetdm/fleet@v4.77.1`
🐹Go	`github.com/fleetdm/fleet`	≥ 4.76.0&&< 4.76.2	4.76.2`go get github.com/fleetdm/fleet@v4.76.2`
🐹Go	`github.com/fleetdm/fleet`	≥ 4.75.0&&< 4.75.2	4.75.2`go get github.com/fleetdm/fleet@v4.75.2`
🐹Go	`github.com/fleetdm/fleet/v4`	all versions	4.43.5-0.20260111020427-0e6c790803d1`go get github.com/fleetdm/fleet/v4@v4.43.5-0.20260111020427-0e6c790803d1`

Affected Products

1 product · 5 configurations

Application

fleetfleetdm

≥ 4.78.0 && < 4.78.2

1 version

4.77.0

Detection & mitigation playbook

Open-source dependency

Detect
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 4.78.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-22808 is resolved across your whole dependency graph.
Workarounds
Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page.

Frequently Asked Questions

### 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 t

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