CVE-2026-26062
Fleet server may terminate unexpectedly when handling certain gRPC requests
Description
### 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 [security@fleetdm.com](mailto:security@fleetdm.com) ### Credits We thank @fuzzztf for responsibly reporting this issue.
How to fix CVE-2026-26062
To remediate CVE-2026-26062, upgrade the affected package to a fixed version below.
- —upgrade to 4.81.0 or later
Is CVE-2026-26062 being exploited?
Low — EPSS is 0.1%, meaning exploitation activity has not been observed at scale.
Affected packages (1)
- from 0, < 4.81.0
CVSS scores
| Source | Version | Severity | Vector |
|---|---|---|---|
| osv | CVSS 4.0 | — | CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N |