CVE-2026-55426 linuxfabrik-lib: Local privilege escalation using embedded command
Attackers can inject commands via monitoring plugin arguments to execute code as root, requiring an upgrade to linuxfabrik-lib and plugins.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-55426?
CVE-2026-55426 is a high-severity command injection vulnerability in Linuxfabrik lib, published on 18 Aug 2026. It can only be exploited from the same machine or local network, with no action from the victim.
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.
Weakness: CWE-78
Which versions are affected by CVE-2026-55426?
3 open source packages ship an affected version, including linuxfabrik-lib.
| Package | Affected | Fixed in |
|---|---|---|
linuxfabrik-lib PyPI | All versions | 5.0.0 |
linuxfabrik-lib PyPI | All versions | 5.0.0 |
linuxfabrik-lib PyPI | All versions | 5.0.0 |
How do I fix CVE-2026-55426?
Upgrade linuxfabrik-lib to 5.0.0 or later.
Upgrade, and pass arguments to programs as a list instead of through a shell. More about Command injection.
Is CVE-2026-55426 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-55426 exists.
Sources
Also known as GHSA-798h-hpph-m24j, PYSEC-2026-2594.