GHSA-GFPW-JGVR-CW4J
Vulnerability from github – Published: 2026-01-20 20:52 – Updated: 2026-01-22 15:38Summary
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 Join #fleet in osquery Slack
Credits
We thank @secfox-ai for responsibly reporting this issue.
{
"affected": [
{
"package": {
"ecosystem": "Go",
"name": "github.com/fleetdm/fleet"
},
"ranges": [
{
"events": [
{
"introduced": "4.78.0"
},
{
"fixed": "4.78.2"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"package": {
"ecosystem": "Go",
"name": "github.com/fleetdm/fleet"
},
"ranges": [
{
"events": [
{
"introduced": "4.77.0"
},
{
"fixed": "4.77.1"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"package": {
"ecosystem": "Go",
"name": "github.com/fleetdm/fleet"
},
"ranges": [
{
"events": [
{
"introduced": "4.76.0"
},
{
"fixed": "4.76.2"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"package": {
"ecosystem": "Go",
"name": "github.com/fleetdm/fleet"
},
"ranges": [
{
"events": [
{
"introduced": "4.75.0"
},
{
"fixed": "4.75.2"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"package": {
"ecosystem": "Go",
"name": "github.com/fleetdm/fleet/v4"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "4.43.5-0.20260111020427-0e6c790803d1"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2026-22808"
],
"database_specific": {
"cwe_ids": [
"CWE-79"
],
"github_reviewed": true,
"github_reviewed_at": "2026-01-20T20:52:17Z",
"nvd_published_at": "2026-01-21T22:15:49Z",
"severity": "MODERATE"
},
"details": "### Summary\n\nA cross-site scripting (XSS) vulnerability in Fleet\u2019s 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.\n\n### Impact\n\nIf 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\u2019s Fleet authentication token from their browser.\n\nA 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.\n\nThis issue does not allow unauthenticated access and does not affect instances where Windows MDM is disabled.\n\n### Patches\n\n- 4.78.2\n- 4.77.1\n- 4.76.2\n- 4.75.2\n- 4.53.3\n\n### Workarounds\n\nIf an immediate upgrade is not possible, affected Fleet users should temporarily disable Windows MDM.\n\n### For more information\n\nIf you have any questions or comments about this advisory:\n\nEmail us at [security@fleetdm.com](mailto:security@fleetdm.com)\nJoin #fleet in [osquery Slack](https://join.slack.com/t/osquery/shared_invite/zt-h29zm0gk-s2DBtGUTW4CFel0f0IjTEw)\n\n### Credits\n\nWe thank @secfox-ai for responsibly reporting this issue.",
"id": "GHSA-gfpw-jgvr-cw4j",
"modified": "2026-01-22T15:38:41Z",
"published": "2026-01-20T20:52:17Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/fleetdm/fleet/security/advisories/GHSA-gfpw-jgvr-cw4j"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-22808"
},
{
"type": "WEB",
"url": "https://github.com/fleetdm/fleet/commit/0e6c790803d1b4407c5b4b41a67a37864a3d3573"
},
{
"type": "PACKAGE",
"url": "https://github.com/fleetdm/fleet"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "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",
"type": "CVSS_V4"
}
],
"summary": "Fleet Windows MDM endpoint has a Cross-site Scripting vulnerability"
}
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Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
Vulnerability timeline
Sightings and recorded dates, grouped by day · UTC
How durations are calculated
Following the VTEM framework (Black Hat USA 2015), time to patch starts when the vendor or a coordinator was informed, total time to patch at discovery, and disclosure to patch at public disclosure; vendor response time runs from the report to its acknowledgement. Time to exploit and time unpatched start at the earliest discovery or report, falling back to public disclosure. Unpatched time ends at the first recorded patch, or the calculation time when no patch is recorded. Exploitation to patch shows the interval between those two events; a published proof of concept is a public exploit, not exploitation.
Each result shows its source dates. A negative interval means the end event came first; when date-only inputs leave the order open, the result says so. Date-only inputs are approximate. The earliest evidence wins: KEV report dates and sightings are labelled as such. Records describing another vulnerability are listed but never calculated from, and a PoC alone does not establish exploitation. Missing patch evidence does not prove that no patch exists. Filters below change the event list only.
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