PYSEC-2026-2595
Vulnerability from pysec - Published: 2026-07-13 15:46 - Updated: 2026-07-13 16:04Summary
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
| Name | purl | linuxfabrik-lib | pkg:pypi/linuxfabrik-lib |
|---|
{
"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"
}
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.