CVE-2026-34388: GO-2026-4915 - Fleet vulnerable to Denial of Service via unhandled gRPC log type in launcher endpoint in github.com/fleetdm/fleet

CVE-2026-34388 · Severity: high · CVSS 7.5 · Published 2026-03-27

Fleet is open source device management software. Prior to 4.81.0, a denial-of-service vulnerability in Fleet's gRPC Launcher endpoint allows an authenticated host to crash the entire Fleet server process by sending an unexpected log type value. The server terminates immediately, disrupting all connected hosts, MDM enrollments, and API consumers. Version 4.81.0 patches the issue.

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

Quick answers

Is CVE-2026-34388 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-34388 being exploited in the wild.
How severe is CVE-2026-34388?
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,fixed=4.81.0.
Is there a fix for CVE-2026-34388?
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.
Am I affected by CVE-2026-34388?
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 4.81.0 or later
    go get github.com/fleetdm/fleet/v4@v4.81.0

Affected products

  • Fleetdm Fleet
  • github.com/fleetdm/fleet/v4 (Go) SEMVER:introduced=0,fixed=4.81.0

Identifiers

  • CVE-2026-34388
  • GHSA-w254-4hp5-7cvv
  • GO-2026-4915

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