CVE-2026-73974 in Monitoring Plugins
Summary
by MITRE • 08/19/2026
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.
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Analysis
by VulDB Data Team • 08/19/2026
The vulnerability identified involves a critical path traversal and information disclosure flaw within the linuxfabrik-lib Python library, specifically affecting versions prior to 6.1.0 and its dependent monitoring plugins before version 7.0.0. This library provides foundational modules for database access, caching, shell execution, and API integrations, serving as a shared testing helper across various Linuxfabrik Monitoring Plugins. The core technical flaw resides in the lib.lftest.test() function, which is designed to facilitate unit testing by simulating standard output or error streams. However, when invoked with a --test CSV argument, this function incorrectly treats either the first or second element of that argument as an arbitrary filesystem path. Crucially, it lacks any form of path confinement or validation, allowing it to read and return the contents of files from anywhere on the system where the executing process has read permissions. This design oversight transforms a testing utility into a powerful file reading mechanism when exposed in production environments.
The operational impact is severe due to the deployment context of these monitoring plugins. These plugins are typically executed with elevated privileges, often via sudo configurations that grant them root-level access to monitor system health effectively. The --test argument, although intended for development and testing purposes, was not adequately restricted or hidden from production execution paths. Consequently, an attacker who has gained control over the nagios or icinga service account can exploit this functionality. By invoking specific check plugins such as deb-updates with its default QUERY parameter set to 1, the attacker can supply a crafted --test argument that points to sensitive root-readable files. The plugin then executes the lib.lftest.test() function, which reads the targeted file and returns its contents directly in the command output. This results in the disclosure of every line from any file accessible by the root user, effectively bypassing standard access controls and exposing critical system configurations, credentials, or private keys to an unauthorized actor with service-level privileges.
Beyond the primary deb-updates plugin, approximately twenty-two other plugins were found to be vulnerable through the same shared helper mechanism. These vulnerabilities allow attackers to perform filtered content disclosure or act as a root file existence and readability oracle, enabling further reconnaissance and privilege escalation attempts. Additionally, two specific plugins, network-bonding and openstack-swift-stat, contained direct read paths that bypassed the lib.lftest.test() helper entirely, yet still suffered from similar path traversal issues due to insufficient input validation on their own execution logic. This widespread exposure across multiple monitoring components significantly expands the attack surface within any infrastructure relying on these tools for system oversight. The ability to read arbitrary files as root undermines the integrity and confidentiality of the entire monitored environment, potentially leading to complete system compromise if combined with other exploitation techniques.
The remediation strategy implemented in linuxfabrik-lib version 6.1.0 addresses this issue by enforcing strict path confinement on fixture reads. The updated library now restricts file access exclusively to the invoking plugin's designated unit-test directory, ensuring that no external or sensitive files can be accessed through the testing helper. It also refuses unsafe anchors and invalid paths, preventing traversal attacks at the code level. For the two plugins with direct read bypasses, network-bonding and openstack-swift-stat, the fix routes their file access logic through this now-secure helper function, ensuring consistent security controls are applied across all components. Administrators must upgrade both linuxfabrik-lib to version 6.1.0 or later and Linuxfabrik Monitoring Plugins to version 7.0.0 or later to mitigate these risks. From a standards perspective, this vulnerability aligns with CWE-22: Improper Limitation of a Pathname to a Restricted Directory, as it allows access outside the intended scope due to insufficient path canonicalization checks. It also relates to ATT&CK technique T1552.004: Unsecured Credentials, specifically involving private keys or other sensitive data stored in files that become readable through this flaw. Immediate patching and verification of sudo configurations for monitoring services are essential steps to restore security posture.