🛡️ CVE-2026-26191 — fleet

🔴 CVSS 9.8 — Critical ✅ No Known Exploit CWE-78 NVD
9.8
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

Fleet vulnerable to OS command injection in software packages

Summary

A vulnerability in Fleet's software installer pipeline could allow a crafted software package to execute arbitrary commands as root (macOS/Linux) or SYSTEM (Windows) on managed endpoints when an uninstall is triggered.

Impact

When a software package (.pkg, .deb, .rpm, .exe, or .msi) is uploaded to Fleet, metadata is extracted from the package binary and used to generate uninstall scripts. In affected versions, this metadata is not properly sanitized before being included in the generated scripts. A specially crafted package containing malicious values in its metadata fields could result in unintended command execution when the uninstall script runs on managed endpoints.

Workarounds

If an immediate upgrade is not possible, administrators should avoid uploading software packages obtained from untrusted or unverified sources. Additionally, administrators can manually inspect and edit auto-generated uninstall scripts before deployment.

For more information

If you have any questions or comments about this advisory:

Email us at [[security@fleetdm.com](mailto:[email protected])](mailto:[email protected])

Join #fleet in [[osquery Slack](https://join.slack.com/t/osquery/shared_invite/zt-h29zm0gk-s2DBtGUTW4CFel0f0IjTEw)](https://join.slack.com/t/osquery/shared_invite/zt-h29zm0gk-s2DBtGUTW4CFel0f0IjTEw)

Credits

We thank @secfox-ai for responsibly reporting this issue.

How this vulnerability can be exploited

This issue can be reached over the network, attack complexity is low, an attacker needs no privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality high, integrity high, availability high.

Weakness class

CVE-2026-26191 is classified as CWE-78: OS Command Injection. Untrusted input reaches a shell command without neutralisation, so an attacker can run arbitrary operating system commands.

Affected software

CVE-2026-26191 is recorded against 3 packages.

  • fleet (fixed in 4.81.0)
  • github.com/fleetdm/fleet/v4
  • unknown

Timeline and source

Published on 14 May 2026 and last revised on 17 June 2026. No public exploit is currently recorded for this entry. Record sourced from NVD.

References

github.com
github.com

Details

Severity CRITICAL
CVSS Score 9.8
CVSS Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CWE CWE-78
Public Exploit ✅ No
Source NVD
Published 2026-05-14
Updated 2026-08-12
Modified 2026-06-17
Fix URL N/A

Affected Packages

Software From version Fixed in
fleet — 4.81.0
github.com/fleetdm/fleet/v4 — —
unknown — —

Similar Threats

Exploit Protection

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