PYSEC-2026-2595

Vulnerability from pysec - Published: 2026-07-13 15:46 - Updated: 2026-07-13 16:04
VLAI
Details

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
Severity
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
Impacted products
Name purl
linuxfabrik-lib pkg:pypi/linuxfabrik-lib
Aliases
To clipboard 

{
  "affected": [
    {
      "package": {
        "ecosystem": "PyPI",
        "name": "linuxfabrik-lib",
        "purl": "pkg:pypi/linuxfabrik-lib"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "5.1.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "2.0.0.0",
        "2.0.0.7",
        "2.1.0.0",
        "2.1.0.4",
        "2.1.1.15",
        "2.1.1.5",
        "2.1.1.7",
        "2.2.0",
        "2.2.1",
        "2.3.0",
        "2.4.0",
        "3.0.0",
        "3.1.0",
        "3.1.1",
        "3.2.0",
        "3.3.0",
        "3.4.0",
        "3.4.1",
        "4.0.0",
        "4.0.1",
        "4.0.2",
        "4.1.0",
        "4.2.0",
        "4.3.0",
        "4.4.0",
        "5.0.0"
      ]
    }
  ],
  "aliases": [
    "CVE-2026-52817",
    "GHSA-8w6w-23mq-h8rg"
  ],
  "details": "### Summary\nIn the [Debian.sudoers](https://github.com/Linuxfabrik/monitoring-plugins/blob/main/assets/sudoers/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:\n\n### PoC\nBy choosing a particular argument, you can get (as a nagios user) a root shell:\n```\nsudo apt-get update -o APT::Update::Pre-Invoke::=\"/bin/sh\"\n```\nSince the nagious user can use sudo to run apt-get as root, the resulting shell is also running as root.\n\n### Impact\nThe 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).\n\n### Fix\nSince only one place where `apt-get` is currently used (in [deb-updates](https://github.com/Linuxfabrik/monitoring-plugins/blob/998302a5fb43e89df1359f4cbb6558f81c96ae4f/check-plugins/deb-updates/deb-updates#L124)) was found, it should be enough to allow only the specific arguments used there.\n\nHere an example how the line in the sudoers file could look like:\n```\n                    /usr/lib64/nagios/plugins/strongswan-connections,\\\n                    /usr/lib64/nagios/plugins/systemd-unit,\\\n                    /usr/bin/apt-get update --quiet 2\n```",
  "id": "PYSEC-2026-2595",
  "modified": "2026-07-13T16:04:36.121072Z",
  "published": "2026-07-13T15:46:27.499597Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/Linuxfabrik/monitoring-plugins/security/advisories/GHSA-8w6w-23mq-h8rg"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/Linuxfabrik/monitoring-plugins"
    },
    {
      "type": "PACKAGE",
      "url": "https://pypi.org/project/linuxfabrik-lib"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/advisories/GHSA-8w6w-23mq-h8rg"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-52817"
    }
  ],
  "severity": [
    {
      "score": "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",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Linuxfabrik Monitoring Plugins: Sudoers may be able to obtain privilege escalation via /usr/bin/apt-get arguments"
}



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