Vulnerability · Published Aug 18, 2026 · Assigned by GitHub_M
CVE-2026-55426linuxfabrik-lib: Local privilege escalation using embedded command
High 7.8
In plain English
A high-severity OS command injection in lib from Linuxfabrik. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 11% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
linuxfabrik-lib provides Python modules for database access, caching, shell execution, and API integrations, and Linuxfabrik Monitoring Plugins uses those modules to run external monitoring commands. From the earliest affected releases until linuxfabrik-lib 5.0.0 and Linuxfabrik Monitoring Plugins 6.0.0, check plugins embedded user-controlled values in command strings passed to lib.shell.shell_exec(), which split strings at pipe characters and executed the resulting commands. In check-plugins/restic-check/restic-check, the --repo parameter could inject a pipe-delimited command into a constructed restic invocation, and sudo-authorized execution allowed a compromised nagios or icinga account to run that command as root. The shared library also accepted command strings and a shell parameter, while numerous plugins constructed external commands from attacker-influenced arguments. The fixes require argv lists, always use shell=False, remove pipe splitting, and reject option-like positional values through lib.shell.safe_cli_value(). These issues are fixed in linuxfabrik-lib 5.0.0 and Linuxfabrik Monitoring Plugins 6.0.0.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| PyPI | linuxfabrik-lib | 5.0.0 | GHSA-798h-hpph-m24j |
| PyPI | linuxfabrik-lib | 5.0.0 | PYSEC-2026-2594 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Linuxfabrik | monitoring-plugins | < 6.0.0 |
| Linuxfabrik | lib | < 5.0.0 |
Weakness: CWE-78 · Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
References
- https://github.com/Linuxfabrik/monitoring-plugins/security/advisories/GHSA-798h-hpph-m24j x_refsource_CONFIRM
- https://github.com/Linuxfabrik/monitoring-plugins/commit/23bb570f41fc8d9caf30b30074bba0e3db1b357a x_refsource_MISC
- https://github.com/Linuxfabrik/lib/blob/main/CHANGELOG.md x_refsource_MISC
- https://github.com/Linuxfabrik/lib/releases/tag/v5.0.0 x_refsource_MISC
- https://github.com/Linuxfabrik/monitoring-plugins/blob/main/CHANGELOG.md x_refsource_MISC
- https://github.com/Linuxfabrik/monitoring-plugins/releases/tag/v6.0.0 x_refsource_MISC