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Fencer Intel
medium 5.5

CVE-2026-73974 json

linuxfabrik-lib: Arbitrary root file read via live --test argument (lib.lftest) across sudoers-whitelisted plugins (LPE)

published 2mo ago modified 2d ago also EUVD-2026-62185 , GHSA-rh9c-rqvg-f7pr , PYSEC-2026-3682

cvss
5.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 6%
public exploits
0
none known

Summary

linuxfabrik-lib provides Python modules for database access, caching, shell execution, and API integrations, and Linuxfabrik Monitoring Plugins uses its shared testing helper across check plugins. Prior to linuxfabrik-lib 6.1.0 and Linuxfabrik Monitoring Plugins 7.0.0, lib.lftest.test() treated the first or second element of a --test CSV argument as a filesystem path and returned the file contents as simulated standard output or standard error without path confinement. The hidden but production-accessible --test argument was accepted by sudo-authorized plugins, so an attacker controlling the nagios or icinga account could use check-plugins/deb-updates/deb-updates with its default QUERY=1 to disclose every line of a root-readable file. Approximately 22 other plugins exposed filtered content or a root file existence and readability oracle through the same helper, while check-plugins/network-bonding/network-bonding and check-plugins/openstack-swift-stat/openstack-swift-stat had direct read paths that bypassed the helper. The library fix confines fixture reads to the invoking plugin's unit-test directory and refuses unsafe anchors, and the plugin fix routes the two bypasses through that helper. These issues are fixed in linuxfabrik-lib 6.1.0 and Linuxfabrik Monitoring Plugins 7.0.0.

Patch / fix

  • pypi linuxfabrik-lib 6.1.0

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CISA SSVC

Exploitation
Proof of concept is public
Automatable
no
Technical impact
partial
Assessed
2mo ago

Exploit prediction

0.17% chance of exploitation in the next 30 days, higher than 6% of all scored CVEs (FIRST EPSS, 2026-11-11).

Exploits and checks

  • github.com https://github.com/Linuxfabrik/monitoring-plugins/security/advisories/GHSA-rh9c-rqvg-f7pr referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 5.5 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
GitHub 3.1 5.5 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
OSV 3.1 5.5 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N

Affected packages

ecosystem package affected fixed in
pypi linuxfabrik-lib
<6.1.0
6.1.0

Affected products

  • Linuxfabrik monitoring-plugins
  • Linuxfabrik lib

Classification

Weakness
  • CWE-22 Improper Limitation of a Pathname to a Restricted Directory
  • CWE-269 Improper Privilege Management

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.