CVE-2026-26061: GO-2026-4889 - Fleet's unbounded request body read allows remote Denial of Service in github.com/fleetdm/fleet

CVE-2026-26061 · Severity: high · CVSS 7.5 · Published 2026-03-27

Fleet is open source device management software. Prior to 4.81.0, Fleet contained multiple unauthenticated HTTP endpoints that read request bodies without enforcing a size limit. An unauthenticated attacker could exploit this behavior by sending large or repeated HTTP payloads, causing excessive memory allocation and resulting in a denial-of-service (DoS) condition. Version 4.81.0 patches the issue.

Technologies: Fleetdm Fleet, github.com/fleetdm/fleet/v4 (Go). Vendors: Fleetdm, Go.

Quick answers

Is CVE-2026-26061 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-26061 being exploited in the wild.
How severe is CVE-2026-26061?
High severity, with a CVSS score of 7.5, published 27 March 2026.
Which products and versions are affected?
github.com/fleetdm/fleet/v4 (Go) SEMVER:introduced=0, SEMVER:introduced=0,fixed=4.43.5-0.20260113202849-bbc1aef2987d.
Is there a fix for CVE-2026-26061?
Yes. github.com/fleetdm/fleet/v4 (Go): upgrade to 4.43.5-0.20260113202849-bbc1aef2987d or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
Am I affected by CVE-2026-26061?
Check whether you run Fleetdm Fleet or 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 4.43.5-0.20260113202849-bbc1aef2987d or later
    go get github.com/fleetdm/fleet/v4@v4.43.5-0.20260113202849-bbc1aef2987d

Affected products

  • Fleetdm Fleet
  • github.com/fleetdm/fleet/v4 (Go) SEMVER:introduced=0, SEMVER:introduced=0,fixed=4.43.5-0.20260113202849-bbc1aef2987d

Identifiers

  • CVE-2026-26061
  • GHSA-99hj-44vg-hfcp
  • GO-2026-4889

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