# CVE-2026-101045: Fleet OS command injection in Homebrew cask metadata handling

Source: https://junglewise.ai/threats/cve-2026-101045-fleet-maintained-app-install-and-uninstall-scripts-for-macos-are  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-27. Updated: 2026-09-27  
License: CC BY 4.0 with a link back

CVE-2026-101045 · Severity: high · CVSS 8 · Published 2026-09-27

Fleet is a device management platform that maintains macOS app installation scripts generated from Homebrew metadata. Before August 19, 2026, these scripts failed to properly escape shell metacharacters in Homebrew cask data, allowing an attacker to inject arbitrary commands. An attacker who could insert crafted malicious metadata into an upstream Homebrew cask could achieve root-level command execution on managed macOS hosts when apps are installed or uninstalled, requiring the payload to pass both Homebrew and Fleet review.

Technologies: [Fleet](https://junglewise.ai/threats/technologies/fleet-fleet). Vendors: [Fleet](https://junglewise.ai/threats/vendors/fleet).

## Quick answers

**Is CVE-2026-101045 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-101045 being exploited in the wild.

**How severe is CVE-2026-101045?** High severity, with a CVSS score of 8, published 27 September 2026.

**Which products and versions are affected?** Fleet Manifests generated before 2026-08-19.

**Is there a fix for CVE-2026-101045?** A patch was published on 2026-08-19: Fix deployed to ingestion pipeline; manifests generated on or after this date escape metadata properly Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-101045 attacked?** It is attacked over the network, in a hosted service.

**Am I affected by CVE-2026-101045?** Check whether you run Fleet at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

OS command injection flaw in Fleet's Homebrew cask ingestion pipeline that failed to escape shell metacharacters (such as command substitution syntax) at all interpolation sites when generating install/uninstall scripts. The vulnerability requires network-level access to influence Homebrew cask metadata upstream, high privileges to inject metadata that survives Homebrew review, and no user interaction; successful exploitation grants arbitrary command execution as root in the context of macOS managed hosts. The fix, deployed August 19, 2026, applies comprehensive escaping across all interpolation points in centrally-generated manifests distributed to all deployments.

## Affected products

- Fleet Fleet Manifests generated before 2026-08-19

## Timeline

- 2026-09-27: disclosed
- 2026-08-19: patched: Fix deployed to ingestion pipeline; manifests generated on or after this date escape metadata properly

## References

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

## Related threats

- [Fleet denial of service via unbounded gzip decompression](https://junglewise.ai/threats/cve-2026-111924-fleet-before-4-83-0-contains-a-denial-of-service-vulnerability)
- [Fleet authorization bypass in MDM command results endpoint](https://junglewise.ai/threats/cve-2026-103265-fleet-versions-before-4-89-0-fail-to-properly-filter-mdm-command)