---
title: "HOST-PKG-004 Many Old Kernels Retained"
canonical: https://openvapt.com/checks/HOST-PKG-004.html
html: https://openvapt.com/checks/HOST-PKG-004.html
site: OpenVAPT, https://openvapt.com/
license: OpenVAPT Source-Available Licence 1.3, https://openvapt.com/legal/licence-text.html
modified: 2026-10-14
version: 0.1.0-alpha.6
---

# HOST-PKG-004 Many Old Kernels Retained

Checks that no more than three kernel versions are installed.

- Domain: Server
- Severity: Low
- Control category: Patch and Vulnerability Management
- Fix effort: low
- CVSS v3.1 vector: `CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:L/I:L/A:N`
- CIS Controls v8: 7.3
- NIST CSF 2.0: ID.RA-01, PR.PS-02
- CWE: CWE-1104
- OWASP Top 10 2021: A06:2021
- NIST SP 800-53 Rev. 5: SI-2, CM-7
- Benchmark topic: Remove unneeded software versions (topic only, no benchmark text)

## Why It Matters

Every installed kernel stays bootable from the boot menu, with every vulnerability it had. Old kernels also fill /boot until updates fail to install, which is a quiet way to stop receiving kernel patches. Keeping the running kernel plus one or two fallbacks is enough.

## How It Detects

Counts kernel versions among installed packages: linux-image-<version> packages whose /var/lib/dpkg/status entry reads 'install ok installed' on Debian and Ubuntu (the /var/lib/dpkg/info/*.list files are used only when the status file cannot be read, because removed but not purged packages keep them), kernel and kernel-core from the allow-listed rpm -qa on the RHEL family. More than three fails. Skipped when no kernel package is installed (containers); Incomplete when no package database could be read.

## How to Fix

Debian/Ubuntu: apt-get autoremove --purge  removes kernels outside the keep list. RHEL family: set installonly_limit=3 in /etc/dnf/dnf.conf and run  dnf remove --oldinstallonly . Never remove the running kernel (uname -r).

## How to Verify

```
dpkg -l 'linux-image-*' | grep '^ii'  or  rpm -q kernel kernel-core
```

## Learn the Theory

- [P1 Linux Server Hardening](https://openvapt.com/academy/p1.md)
- [P22 Authentication Policy and Package Hygiene](https://openvapt.com/academy/p22.md)

## References

- [NIST SP 800-40 Rev. 4, Guide to Enterprise Patch Management Planning](https://csrc.nist.gov/pubs/sp/800/40/r4/final)
- [apt-get(8), Debian trixie manual pages (autoremove)](https://manpages.debian.org/trixie/apt/apt-get.8.en.html)

## Source Code

https://github.com/OpenVAPT/openvapt/blob/574f7f3333c44b75a3c649e2d93a76d507f75adf/internal/checks/host/pkg_depth.go

Run it: `openvapt scan --only HOST-PKG-004`. Read it offline: `openvapt explain HOST-PKG-004`.

---

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