CVE-2026-26062 is a high-severity improper input validation vulnerability in github.com/fleetdm/fleet/v4 (go), affecting versions < 4.81.0. It is fixed in 4.81.0.
Summary Fleet contained a denial-of-service (DoS) issue in the gRPC Launcher PublishLogs endpoint. In affected versions, certain unexpected input values were not handled gracefully, which could cause the Fleet server process to terminate while processing an authenticated request from an enrolled Launcher host. Impact An authenticated attacker with access to any enrolled Launcher node key could cause an immediate and complete denial of service by sending a single gRPC request to the PublishLogs endpoint. This vulnerability impacts availability only. There is: No exposure of sensitive data No authentication bypass No privilege escalation No integrity impact Workarounds If upgrading immediately is not possible, the following mitigations can reduce exposure: Restrict network access to the Fleet gRPC endpoint where feasible (for example, limiting inbound access to known host IP ranges). Deploy Fleet behind infrastructure that terminates or filters gRPC traffic if Launcher log ingestion is not required. Monitor for repeated Fleet process crashes or unexpected restarts indicating potential exploitation. For More Information If you have any questions or concerns about this advisory, please contact us at: Email us at [email protected] Credits We thank @fuzzztf for responsibly reporting this issue.
The application does not adequately validate input before processing it, allowing unexpected values to reach sensitive code paths. Typical impact: varies by context: data corruption, logic bypass, or denial of service.
go
github.com/fleetdm/fleet/v4 (< 4.81.0)github.com/fleetdm/fleet/v4 → 4.81.0 (go)Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
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Already deployed Kodem? See CVE-2026-26062 in your environment →Upgrade github.com/fleetdm/fleet/v4 to 4.81.0 or later to resolve this vulnerability.
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CVE-2026-26062 is a high-severity improper input validation vulnerability in github.com/fleetdm/fleet/v4 (go), affecting versions < 4.81.0. It is fixed in 4.81.0. The application does not adequately validate input before processing it, allowing unexpected values to reach sensitive code paths.
github.com/fleetdm/fleet/v4 (go) versions < 4.81.0 is affected.
Yes. CVE-2026-26062 is fixed in 4.81.0. Upgrade to this version or later.
Whether CVE-2026-26062 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
Upgrade github.com/fleetdm/fleet/v4 to 4.81.0 or later.