Which versions of Monitoring Plugins are affected by CVE-2026-52817?

Linuxfabrik Monitoring Plugins versions 5.0.0 and earlier contain a local privilege escalation that allows compromised monitoring service accounts to gain root access on Debian systems.. A patch is available.

How to fix or mitigate CVE-2026-52817?

Within 24 hours, inventory all Debian systems running Linuxfabrik Monitoring Plugins and identify those on version 5.0.0 or earlier. Within 7 days, patch affected systems to version 5.1.0 or later, beginning with production environments. Within 30 days, verify completion of the upgrade across all deployments and document the patching record for compliance.

Monitoring Plugins CVE-2026-52817

Q: What is the CVSS score of CVE-2026-52817?

CVE-2026-52817 has a CVSS 4.0 base score of 7.0 (High). CVSS vector: CVSS:4.0/AV:L/AC:L/AT:N/PR:H/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:P/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X. EPSS exploitation probability: 0.2%.

EUVD-2026-61489 HIGH

Improper Neutralization of Argument Delimiters in a Command ('Argument Injection') (CWE-88)

2026-07-02 https://github.com/Linuxfabrik/monitoring-plugins

GHSA-8w6w-23mq-h8rg PYSEC-2026-2595

Privilege Escalation Debian

7.0

CVSS 4.0 · Vendor: https://github.com/Linuxfabrik/monitoring-plugins

Severity by source

Vendor (https://github.com/Linuxfabrik/monitoring-plugins) PRIMARY

7.0 HIGH

CVSS:4.0/AV:L/AC:L/AT:N/PR:H/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:P/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

vuln.today AI

6.7 MEDIUM

Local-only attack (AV:L) requiring an established nagios session (PR:H, AC:L); scope unchanged as root shell remains on the same host (S:U); full C/I/A impact once escalated.

3.1 AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H

4.0 AV:L/AC:L/AT:N/PR:H/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

Primary rating from Vendor (https://github.com/Linuxfabrik/monitoring-plugins).

CVSS VectorVendor: https://github.com/Linuxfabrik/monitoring-plugins

Attack Vector

Local

Attack Complexity

Low

Privileges Required

High

User Interaction

None

Scope

Lifecycle Timeline

Source Code Evidence Fetched

Aug 18, 2026 - 21:28 vuln.today

Analysis Updated

Aug 18, 2026 - 21:28 vuln.today

v2 (cvss_changed)

Re-analysis Queued

Aug 18, 2026 - 21:22 vuln.today

cvss_changed

CVSS changed

Aug 18, 2026 - 21:22 NVD

7.0 (HIGH)

Analysis Generated

Jul 02, 2026 - 20:50 vuln.today

DescriptionCVE.org

Summary

In the Debian.sudoers file, apt-get is allowed for the nagios user. The full command including the arguments are not enforced and can therefore be choosen arbitrarily. This allows to easily get a root shell as the nagios user:

PoC

By choosing a particular argument, you can get (as a nagios user) a root shell:

sudo apt-get update -o APT::Update::Pre-Invoke::="/bin/sh"

Since the nagious user can use sudo to run apt-get as root, the resulting shell is also running as root.

Impact

The vulnerability is a local privilege escalation, impacting users who use the provided sudoers file. It requires that an attacker already compromised the nagios account (which is quite a high barrier to be honest).

Fix

Since only one place where apt-get is currently used (in deb-updates) was found, it should be enough to allow only the specific arguments used there.

Here an example how the line in the sudoers file could look like:

                    /usr/lib64/nagios/plugins/strongswan-connections,\
                    /usr/lib64/nagios/plugins/systemd-unit,\
                    /usr/bin/apt-get update --quiet 2

AnalysisAI

Local privilege escalation in Linuxfabrik Monitoring Plugins allows the nagios monitoring user to obtain a root shell on Debian systems by injecting arbitrary arguments into an unrestricted apt-get sudoers rule. Deployments running version 5.0.0 or earlier with the bundled Debian.sudoers file installed are affected; exploitation requires prior compromise of the nagios account. A public proof-of-concept is documented in the vendor advisory, and a confirmed fix is available in version 5.1.0 released 2026-05-30.

Technical ContextAI

The affected component is the Debian.sudoers file distributed with Linuxfabrik Monitoring Plugins (pip package linuxfabrik-lib, CPE pkg:pip/linuxfabrik-lib). The file grants the nagios user passwordless sudo access to /usr/bin/apt-get without restricting which arguments may be passed. CWE-88 (Argument Injection) identifies the root cause: apt-get's -o flag accepts APT runtime configuration options, including Pre-Invoke hooks that execute arbitrary shell commands before the update process. Because the Cmnd_Alias in the sudoers file was defined as the bare binary path /usr/bin/apt-get with no argument constraints, any argument combination is permitted under the grant. The fix - confirmed in commit 694b5dae - narrows the sudoers entry to the exact invocation /usr/bin/apt-get update --quiet 2 that the deb-updates plugin legitimately requires.

RemediationAI

Upgrade Linuxfabrik Monitoring Plugins to version 5.1.0 or later; the fix is confirmed in commit 694b5daeebadc9a51428f3de1acff7b1f737642f and restricts the sudoers apt-get grant to the exact invocation /usr/bin/apt-get update --quiet 2, eliminating the argument injection surface entirely. Full advisory and release details are available at https://github.com/Linuxfabrik/monitoring-plugins/security/advisories/GHSA-8w6w-23mq-h8rg. If an immediate upgrade is not possible, manually edit the deployed sudoers file (typically in /etc/sudoers.d/) to replace the unrestricted /usr/bin/apt-get entry with /usr/bin/apt-get update --quiet 2; this workaround has no functional side effect on the deb-updates plugin, which calls apt-get with exactly those arguments. Additionally, audit the entire deployed sudoers file for other command grants that omit argument constraints, as the same argument-injection technique may apply to other listed binaries.