Fleet-maintained app install and uninstall scripts for macOS are generated from Homebrew cask…

Why it is Yellow

• CVSS 8.0 high

References

• https://github.com/fleetdm/fleet/security/advisories/GHSA-fv3p-h7wv-2jgm
• https://www.vulncheck.com/advisories/fleet-homebrew-cask-os-command-injection-via-metadata

Original description

Fleet-maintained app install and uninstall scripts for macOS are generated from Homebrew cask metadata. In manifests generated before 2026-08-19, the script generator escaped this metadata at some interpolation sites but not all of them, so cask metadata containing shell metacharacters (for example $(...) command substitution) could be carried into scripts that execute as root on managed macOS hosts. An attacker who could land crafted metadata in an upstream Homebrew cask — without needing any Fleet credentials — could achieve arbitrary command execution as root on managed macOS hosts that install or uninstall the affected Fleet-maintained app; exploitation required the crafted metadata to pass both upstream Homebrew cask review and Fleet's review of the automated ingestion pull request. The fix (fleetdm/fleet#51324) landed in Fleet's ingestion pipeline on 2026-08-19 so that all manifests generated on or after that date escape cask metadata at every interpolation site; because manifests are generated centrally and distributed as pre-built content, remediation applied to all deployments with no customer action, and the code fix is included in Fleet v4.92.0.