CVE-2026-26061 Fleet's unbounded request body read allows remote Denial of Service
Unauthenticated attackers can cause denial of service in Fleet by sending large HTTP payloads to endpoints lacking size limits.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-26061?
CVE-2026-26061 is a high-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, 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.
Weakness: CWE-770
Which versions are affected by CVE-2026-26061?
3 open source packages ship an affected version, including github.com/fleetdm/fleet/v4. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
github.com/fleetdm/fleet/v4 Go | All versions | None |
github.com/fleetdm/fleet/v4 Go | All versions | 4.43.5-0.20260113202849-bbc1aef2987d |
github.com/fleetdm/fleet/v4 Go | All versions | 4.43.5-0.20260113202849-bbc1aef2987d |
Products include Fleetdm Fleet.
How do I fix CVE-2026-26061?
Upgrade github.com/fleetdm/fleet/v4 to 4.43.5-0.20260113202849-bbc1aef2987d 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-2026-26061 being exploited?
There is no known exploitation of CVE-2026-26061 in the wild and no public exploit code.
Other vulnerabilities in fleetdm fleet
- CVE-2020-26276 SAML authentication vulnerability in Fleet
- CVE-2026-103264 Fleet before 4.87.0 Authentication Bypass via Device Identifiers
- CVE-2026-23518 Fleet has a JWT signature bypass vulnerability in Azure AD MDM enrollment
- CVE-2026-26062 Fleet server may terminate unexpectedly when handling certain gRPC requests
- CVE-2026-23998 Fleet has a Windows MDM management endpoint authentication bypass
Sources
Also known as GHSA-99hj-44vg-hfcp, GO-2026-4889.