CVE-2026-22808
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedfleetdm/fleet is open source device management software. Prior to versions 4.78.2, 4.77.1, 4.76.2, 4.75.2, and 4.53.3, if Windows MDM is enabled, an unauthenticated attacker can exploit this XSS vulnerability to steal a Fleet administrator's authentication token (FLEET::auth_token) from localStorage. This could allow unauthorized access to Fleet, including administrative access, visibility into device data, and modification of configuration. Versions 4.78.2, 4.77.1, 4.76.2, 4.75.2, and 4.53.3 fix the issue. If an immediate upgrade is not possible, affected Fleet users should temporarily disable Windows MDM.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidenceThis is a stored XSS vulnerability in Fleet's Windows MDM feature that allows unauthenticated attackers to inject malicious scripts that can access the Fleet administrator's authentication token (FLEET::auth_token) stored in the browser's localStorage, enabling unauthorized administrative access to the Fleet platform.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data< 4.53.3>= 4.75.0, < 4.75.2>= 4.76.0, < 4.76.2>= 4.78.0, < 4.78.2= 4.77.0CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- Low
- User interaction
- Required
- Scope
- Changed
- Confidentiality
- Low
- Integrity
- Low
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Identify Fleet versionCheck the installed Fleet version via the UI (usually in the footer of any Fleet page) or by querying the Fleet server API endpoint /api/latest/version or checking the docker/container version if running in containersAffected if The installed version falls into one of these ranges: < 4.53.3; >= 4.75.0 and < 4.75.2; >= 4.76.0 and < 4.76.2; >= 4.78.0 and < 4.78.2; or exactly 4.77.0
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Verify Windows MDM feature statusNavigate to Fleet settings or the MDM section in the Fleet UI and check whether Windows MDM (Windows Device Management) is enabled or configured. Alternatively, query the Fleet API for MDM configuration statusAffected if Windows MDM feature is enabled or has been configured with any MDM profiles
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Review MDM profile content for injected scriptsInspect any MDM profiles or configurations stored in Fleet's database or UI, specifically looking for suspicious JavaScript tags, event handlers, or encoded payloads within profile fields, especially in Windows MDM profile settingsAffected if Any MDM profile contains script tags, javascript: URIs, or unusual event handlers that could indicate XSS payload injection
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Check browser localStorage for unauthorized accessIf you are a Fleet administrator, open the Fleet web interface in a browser, open developer tools (F12), go to Application > Local Storage, and examine the FLEET::auth_token value for any signs of compromise or unauthorized session tokensAffected if Multiple or unexpected auth_token values exist in localStorage, or the token was generated from an unknown source
You are affected if your Fleet version is in any of the affected ranges AND the Windows MDM feature is enabled, as the XSS vulnerability resides specifically in the Windows MDM functionality.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
dbcve · scoped4.53.34.75.24.76.2
Upgrade to one of the patched versions (4.78.2, 4.77.1, 4.76.2, 4.75.2, or 4.53.3). If immediate upgrade is not feasible, temporarily disable the Windows MDM feature as a compensating control.
Upgrade to 4.78.2 (or the appropriate fixed version for your branch: 4.53.3, 4.75.2, 4.76.2, or 4.77.1)
- 1. Identify your current Fleet version by checking the Fleet UI or running `fleetctl --version`
- 2. Determine which upgrade path applies based on your current version: if on 4.53.x upgrade to 4.53.3; if on 4.75.x upgrade to 4.75.2; if on 4.76.x upgrade to 4.76.2; if on 4.77.x or 4.78.x upgrade to 4.78.2
- 3. Review Fleet upgrade documentation for your deployment method (Kubernetes, Docker, or native binary)
- 4. Perform the upgrade following standard Fleet upgrade procedures for your environment
- 5. After upgrade, verify Windows MDM functionality remains working as expected
- 6. Confirm the fix by checking that the XSS vulnerability is no longer present in the Fleet instance
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation2.0 h
- Implementation2.0 h
- Testing3.0 h
- Review / QA2.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-22808 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-22808 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
- No weaponised exploit code, or anything meant to cause harm
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