CVE-2026-23998: Fleet is open source device management software

Q: How do I fix CVE-2026-23998?

fleet: upgrade to 4.81.0. Exact commands for each OS are on this page.

Q: Is CVE-2026-23998 being exploited?

CVE-2026-23998 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2026-23998 affect?

CVE-2026-23998 affects fleet. Severity is high (CVSS 7.5). Fleet is open source device management software. Prior to version 4.81.0, a vulnerability in Fleet’s Windows MDM management endpoint could allow requests to be processed without proper client certificate validation. In certain circumstances

Q: How urgent is CVE-2026-23998?

Priority 34/100. High severity; Remotely exploitable, no login, no user action

Routine

HIGH 7.5REMOTEUPGRADE

CVE-2026-23998 is a high-severity flaw (CVSS 7.5) affecting fleet. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Fleet is open source device management software. Prior to version 4.81.0, a vulnerability in Fleet’s Windows MDM management endpoint could allow requests to be processed without proper client certificate validation. In certain circumstances, this could allow an attacker to impersonate an enrolled Windows device and retrieve sensitive configuration data. Fleet’s Windows MDM management endpoint relies on mutual TLS (mTLS) client certificates to aut

Why this priority

High severity
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.2% (top 88%)
CISA exploited list	No
Weakness	CWE-295
Published	2026-05-14
Last modified	2026-10-26

Publisher (CNA): GitHub, Inc. · Vendor: fleetdm

Last updated 2026-10-26 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-05-14 19:16 UTCPublished CVE record published
2026-10-26 14:10 UTCUpdated Record last modified

fleetdm fleet UPGRADE

Affected: < 4.81.0

Fixed in: 4.81.0

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy fleet || rpm -q fleet || fleet --version

2. UPGRADE to 4.81.0 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade fleet

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade fleet

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-23998?

fleet: upgrade to 4.81.0. Exact commands for each OS are on this page.

Is CVE-2026-23998 being exploited?

CVE-2026-23998 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-23998 affect?

CVE-2026-23998 affects fleet. Severity is high (CVSS 7.5). Fleet is open source device management software. Prior to version 4.81.0, a vulnerability in Fleet’s Windows MDM management endpoint could allow requests to be processed without proper client certificate validation. In certain circumstances

How urgent is CVE-2026-23998?

Priority 34/100. High severity; Remotely exploitable, no login, no user action

Software pages

Windows vulnerabilities

Related CVEs

CVE-2026-26191 CRITICAL 9.8 UPGRADE Fleet is open source device management software
CVE-2026-24899 HIGH 7.5 UPGRADE Fleet is open source device management software
CVE-2026-46356 HIGH 7.5 UPGRADE Fleet is open source device management software
CVE-2026-24000 MEDIUM 5.3 UPGRADE Fleet is open source device management software
CVE-2026-26062 MEDIUM 6.5 UPGRADE Fleet is open source device management software

References

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