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.

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

Q: 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.

Q: How is CVE-2026-23998 attacked?

It is attacked over the network, in a network appliance.

Q: 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.

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). 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
```
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

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