CVE-2026-34389 Fleet's user account creation via invite does not enforce invited email address

What is CVE-2026-34389?

CVE-2026-34389 is a medium-severity authentication bypass vulnerability in fleetdm fleet, published on 27 Mar 2026. Any signed-in user can exploit it over the network, with no action from the victim.

Official description

Fleet is open source device management software. Prior to 4.81.0, Fleet contained an issue in the user invitation flow where the email address provided during invite acceptance was not validated against the email address associated with the invite. An attacker who obtained a valid invite token could create an account under an arbitrary email address while inheriting the role granted by the invite, including global admin. Version 4.81.0 patches the issue.

Weakness: CWE-287

Which versions are affected by CVE-2026-34389?

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-2026-34389?

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

Upgrade, and rotate credentials and sessions that may have been exposed. More about Authentication bypass.

Is CVE-2026-34389 being exploited?

There is no known exploitation of CVE-2026-34389 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-4f9r-x588-pp2h, GO-2026-4912.