CVE-2026-55426: Linuxfabrik Monitoring Plugins OS command injection in shell_exec

CVE-2026-55426 · Severity: high · CVSS 7.8 · Published 2026-07-06

Linuxfabrik Monitoring Plugins, used for system health monitoring, contain a vulnerability that allows a local user to execute unauthorized commands with elevated privileges. By providing specially crafted input to certain plugins, such as the restic-check plugin, an attacker can bypass security restrictions and potentially gain full administrative (root) control over the system. This could lead to complete system compromise, data theft, or service disruption.

Technologies: Linuxfabrik Monitoring-Plugins, linuxfabrik-lib (PyPI). Vendors: Linuxfabrik, PyPI.

Quick answers

Is CVE-2026-55426 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-55426 being exploited in the wild.
How severe is CVE-2026-55426?
High severity, with a CVSS score of 7.8, published 6 July 2026.
Which products and versions are affected?
Linuxfabrik Monitoring-Plugins <= 5.2.0; linuxfabrik-lib (PyPI) < 5.0.0, ECOSYSTEM:introduced=0,fixed=5.0.0.
Is there a fix for CVE-2026-55426?
Yes. linuxfabrik-lib (PyPI): upgrade to 5.0.0 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-55426 attacked?
It is attacked with local access, in a software library.
Am I affected by CVE-2026-55426?
Check whether you run Linuxfabrik Monitoring-Plugins or linuxfabrik-lib (PyPI) 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.

How to fix

  • linuxfabrik-lib (PyPI): upgrade to 5.0.0 or later
    pip install "linuxfabrik-lib>=5.0.0"

Technical details

A command injection vulnerability (CWE-78) exists in Linuxfabrik Monitoring Plugins and the underlying linuxfabrik-lib. The `lib.shell.shell_exec()` function improperly handled user-provided input by allowing command chaining via the pipe ('|') character and failing to sanitize arguments. An attacker with local access (e.g., the 'nagios' user) can provide malicious arguments to plugins often listed in sudoers, such as `restic-check --repo`, to execute arbitrary commands as root. The vulnerability was addressed in linuxfabrik-lib 5.0.0 and Monitoring Plugins v5.2.0 by transitioning to an argv list approach for command execution and disabling shell evaluation.

Affected products

  • Linuxfabrik linuxfabrik-lib < 5.0.0
  • Linuxfabrik Monitoring Plugins <= 5.2.0

Identifiers

  • CVE-2026-55426
  • GHSA-798h-hpph-m24j
  • PYSEC-2026-2594

Timeline

  • 2026-06-12: disclosed: Initial disclosure by researcher
  • 2026-07-06: advisory: GitHub Advisory published

References

This page as Markdown. Free to reuse under CC BY 4.0 with a link back.