CVE-2026-34388 Fleet vulnerable to Denial of Service via unhandled gRPC log type in launcher endpoint

What is CVE-2026-34388?

CVE-2026-34388 is a medium-severity denial of service vulnerability in fleetdm fleet, published on 27 Mar 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

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.

Weakness: CWE-703

Which versions are affected by CVE-2026-34388?

3 open source packages ship an affected version, including github.com/fleetdm/fleet/v4. It affects 1 product.

Products include Fleetdm Fleet.

How do I fix CVE-2026-34388?

Upgrade github.com/fleetdm/fleet/v4 to 4.81.0 or later.

Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.

Is CVE-2026-34388 being exploited?

There is no known exploitation of CVE-2026-34388 in the wild and no public exploit code.

Other vulnerabilities in fleetdm fleet

• CVE-2020-26276 SAML authentication vulnerability in Fleet Critical 10.0
• CVE-2026-103264 Fleet before 4.87.0 Authentication Bypass via Device Identifiers Critical 9.3
• CVE-2026-23518 Fleet has a JWT signature bypass vulnerability in Azure AD MDM enrollment Critical 9.3
• CVE-2026-26062 Fleet server may terminate unexpectedly when handling certain gRPC requests High 8.7
• CVE-2026-26061 Fleet's unbounded request body read allows remote Denial of Service High 8.7

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as GHSA-w254-4hp5-7cvv, GO-2026-4915.