Linuxfabrik Monitoring Plugins have local privilege escalation using embedded command

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

7.8 · CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

EPSS

• CVE-2026-55426: 0.21% estimated exploitation activity in the next 30 days; percentile 11.38 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary When a check plugin places user provided input inside a command which is passed to shellexec, an attacker can abuse this to run arbitrary commands. This is mainly dangerous for plugins which are listed in the sudoers file, because this allows an attacker controlling the nagios user to get root privileges. Details An example for this is the restic-check plugin, where the --repo argument is placed inside the command argument of shellexec. As an example, an attacker could use the --repo argument |touch /root/nagios-was-here|. The full restic command is assembled to the string restic --json --repo=|touch /root/nagios-was-here| --password-file= check before it is passed to shellexec. shellexec then splits the command up in three parts at the | boundaries and executes the parts separately, which also executes the embedded command touch /root/nagios-was-here. PoC This PoC shows how the nagios user can use this to create a file inside /root. Impact The vulnerability is a local…

Published by the source

6 Jul 2026, 21:13 UTC

Last modified by the source

13 Jul 2026, 16:43 UTC

Source last checked

26 Oct 2026, 13:46 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-798h-hpph-m24j

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-798h-hpph-m24j

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# Patch Next advisory brief: CVE-2026-55426

Advisory: Linuxfabrik Monitoring Plugins have local privilege escalation using embedded command
IDs: CVE-2026-55426, GHSA-798h-hpph-m24j
Record: https://patchnext.com/advisories/cve-2026-55426 (revision 2, source checked 26 Oct 2026, 13:46 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.8)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: linuxfabrik-lib 5.0.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI linuxfabrik-lib: affected < 5.0.0; fixed in 5.0.0

## Suggested inspection (read-only)
- `python -m pip show linuxfabrik-lib`: prints the installed version. Run with the environment that serves production active.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on linuxfabrik-lib.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-798h-hpph-m24j (OSV record GHSA-798h-hpph-m24j lists affected ranges: PyPI linuxfabrik-lib >=0 <5.0.0 (fixed))
- Verified: https://github.com/advisories/GHSA-798h-hpph-m24j (GitHub-reviewed advisory GHSA-798h-hpph-m24j lists affected ranges: PyPI linuxfabrik-lib >=0 <5.0.0)

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