CVE-2026-55426: Linuxfabrik lib · OS Command Injection
Affects Linuxfabrik libSource CVE Database V5
Public exploit available · CVSS 7.8 High : upgrade to 5.0.0 as a priority.
Data as of 26 Oct 2026, 10:12 UTC
- EPSS
- 0.2% chance of exploitation in 30 days – higher than 11% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- CISA SSVC
- Exploitation
- Proof of concept is public or traded
- Automatable
- Attackers cannot reliably automate steps 1–4 of the kill chain
- Technical impact
- Total control over the software or total information disclosure
CISA SSVC assessment, 2026-08-19.
- Patch
- Available – fixed in 6.0.0, 5.0.0
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:HExploitation evidence
t = 0 is the CVE’s publication on cve.org
Disclosed: evidence found.
CVE published 18 Aug 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: evidence found.
CISA SSVC: proof of concept public
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
Timeline
CVE ID reserved
by GitHub, Inc.
, 63 days before disclosure
CVE published
on cve.org
, t = 0
CISA SSVC assessment
proof of concept public
, 24 hours after disclosure
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), CISA SSVC, the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.
What to do
Upgrade lib to 5.0.0; monitoring-plugins to 6.0.0.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| Linuxfabrikmonitoring-plugins | Affected
| Fixed in
|
| Linuxfabriklib | Affected
| Fixed in
|
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.
References
- github.com/Linuxfabrik/monitoring-plugins/security/advisories/GHSA-798h-hpph-m24j (opens in a new tab)
- github.com/Linuxfabrik/monitoring-plugins/commit/23bb570f41fc8d9caf30b30074bba0e3db1b357a (opens in a new tab)
- github.com/Linuxfabrik/lib/blob/main/CHANGELOG.md (opens in a new tab)
- github.com/Linuxfabrik/lib/releases/tag/v5.0.0 (opens in a new tab)
- github.com/Linuxfabrik/monitoring-plugins/blob/main/CHANGELOG.md (opens in a new tab)
- github.com/Linuxfabrik/monitoring-plugins/releases/tag/v6.0.0 (opens in a new tab)