# CVE-2026-23998: Fleet Device Management authentication bypass in Windows MDM endpoint

Source: https://junglewise.ai/threats/cve-2026-23998-fleet-device-management-authentication-bypass-in-windows-mdm  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-05-14. Updated: 2026-05-16  
License: CC BY 4.0 with a link back

CVE-2026-23998 · Severity: high · CVSS 7.5 · Published 2026-05-14

Fleet is an open-source platform used by IT and security teams to manage and secure fleets of laptops and servers. A security flaw in the Windows device management component could allow an attacker to bypass authentication and impersonate a legitimate Windows computer. If successful, an attacker could steal sensitive configuration data intended for that device, such as Wi-Fi passwords, VPN credentials, and security certificates.

Technologies: [github.com/fleetdm/fleet/v4 (Go)](https://junglewise.ai/threats/technologies/github-com-fleetdm-fleet-v4). Vendors: [Go](https://junglewise.ai/threats/vendors/go).

## Quick answers

**Is CVE-2026-23998 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-23998 being exploited in the wild.

**How severe is CVE-2026-23998?** High severity, with a CVSS score of 7.5, published 14 May 2026.

**Which products and versions are affected?** github.com/fleetdm/fleet/v4 (Go) < 4.81.0, SEMVER:introduced=0,fixed=4.81.0.

**Is there a fix for CVE-2026-23998?** Yes. github.com/fleetdm/fleet/v4 (Go): upgrade to 4.81.0 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-23998 attacked?** It is attacked over the network, in a network appliance.

**Am I affected by CVE-2026-23998?** Check whether you run github.com/fleetdm/fleet/v4 (Go) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- github.com/fleetdm/fleet/v4 (Go): upgrade to 4.81.0 or later

  ```sh
  go get github.com/fleetdm/fleet/v4@v4.81.0
  ```


## Technical details

A vulnerability exists in Fleet's Windows MDM management endpoint due to improper certificate validation (CWE-295). The endpoint is intended to require mutual TLS (mTLS) for authentication; however, affected versions may incorrectly trust requests that fail to present a valid client certificate. An attacker with knowledge of a specific enrolled device identifier can exploit this to impersonate that device and retrieve its MDM configuration payloads. These payloads often contain sensitive secrets including VPN/Wi-Fi configurations and certificates. The attack requires network access to the MDM endpoint and prior knowledge of a device ID, but does not require valid credentials or user interaction. The issue is fixed in version 4.81.0.

## Affected products

- Fleet Device Management (fleetdm) Fleet < 4.81.0

## Identifiers

- CVE-2026-23998
- GHSA-2rc4-7jc6-qffh
- GO-2026-5002

## Timeline

- 2026-02-20: patched: Version 4.81.0 released
- 2026-05-13: disclosed: Initial advisory publication
- 2026-05-14: advisory: GitHub Advisory published/reviewed

## References

- [https://github.com/fleetdm/fleet/security/advisories/GHSA-2rc4-7jc6-qffh](https://github.com/fleetdm/fleet/security/advisories/GHSA-2rc4-7jc6-qffh)
- [https://github.com/fleetdm/fleet/releases/tag/fleet-v4.81.0](https://github.com/fleetdm/fleet/releases/tag/fleet-v4.81.0)
- [https://api.github.com/repos/fleetdm/fleet/security-advisories/GHSA-2rc4-7jc6-qffh](https://api.github.com/repos/fleetdm/fleet/security-advisories/GHSA-2rc4-7jc6-qffh)

## Related threats

- [Fleet SQL injection in Okta conditional access endpoint](https://junglewise.ai/threats/cve-2026-54245-fleet-sql-injection-in-okta-conditional-access-endpoint)
- [Fleet SQL injection in Apple MDM commands endpoint](https://junglewise.ai/threats/cve-2026-46371-fleet-sql-injection-in-apple-mdm-commands-endpoint)
- [Fleet SQL injection in labels host-listing endpoint](https://junglewise.ai/threats/cve-2026-46370-fleet-sql-injection-in-labels-host-listing-endpoint)
- [Fleet information disclosure in target search endpoint](https://junglewise.ai/threats/cve-2026-48786-fleet-information-disclosure-in-target-search-endpoint)
- [Fleet DM cross-team policy data exposure in global policy endpoint](https://junglewise.ai/threats/cve-2026-41262-fleet-dm-cross-team-policy-data-exposure-in-global-policy)