---
title: "CVE-2026-109518: APT RCE via hard link reuse"
url: https://erroneo.us/security/cve/CVE-2026-109518/
description: "CVE-2026-109518 (Debian APT): On Debian, Ubuntu, and derivative Linux distributions, an on-path attacker who can manipulate the HTTP traffic (including a…"
type: vulnerability-record
section: "Security Digest"
date_published: 2026-11-04
date_modified: 2026-11-05
publisher: erroneo.us
author: erroneo.us Security Desk
cve: "CVE-2026-109518"
kev: false
cvss: 7.7
epss: null
license: All rights reserved. Quote with attribution and a link.
---

# CVE-2026-109518: APT RCE via hard link reuse

**Signal:** Normal patch cycle. No exploitation signal; fix it in your next routine update if you are affected. (Computed from CISA KEV, EPSS and CVSS; not an editorial verdict.)

## Should you act?

- No confirmed exploitation. It is not in CISA’s KEV catalog and CISA’s SSVC assessment records no known exploitation. That can change quickly after a public write-up; re-check if you are affected.
- Editorial verdict: Patch this week. APT CVE-2026-109518: Package Swap to Root on Debian/Ubuntu — Nobody is known to be exploiting it and the attacker must sit between you and your mirror, but APT is the trust root for every Debian and Ubuntu machine and image you build, so update apt itself this week and rebuild base images.

## What it is

On Debian, Ubuntu, and derivative Linux distributions, an on-path attacker who can manipulate the HTTP traffic (including a malicious mirror or proxy) between an APT client and an archive server triggered by a package install can trick the client into installing an attacker-controlled unverified package and achieve remote code execution with root privileges. The vulnerability is caused by the reuse of hard links and requires the client to follow redirects and retry the download of package files. It requires the client to have a non-zero Acquire::Retries configuration setting; the value 3 is the default starting with Debian 12 (bookworm) and Ubuntu 22.04 LTS (Jammy Jellyfish), so older releases are unaffected in a default configuration

## Affected products (CVE record)

- Debian APT: < 1.2.36, 1.4.0 < 1.4.12, 1.6.0 < 1.6.19, 1.8.0 < 1.8.2.4, 1.8.3 <= 1.8.5, 2.0.0 < 2.0.12, 2.2.0 < 2.2.5, 2.4.0 < 2.4.15, 2.6.0 < 2.6.2, 2.8.0 < 2.8.4, 3.0.0 < 3.0.4, 3.2.0 < 3.2.1
- Ubuntu APT: < 1.0.1ubuntu2.24+esm4, 1.2.0 < 1.2.36+esm1, 1.6.0 < 1.6.19+esm1, 2.0.0 < 2.0.12+esm1, 2.4.0 < 2.4.15ubuntu0.1, 2.8.0 < 2.8.4ubuntu0.1, 3.2.0 < 3.2.1ubuntu0.1, 3.3.0 < 3.3.3ubuntu0.1

## Severity

- canonical CVSS 4.0: 7.7 `CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N`

## Exploitation

- CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
- CISA SSVC assessment: exploitation none , automatable no , technical impact total .

## Sources

- [lists.debian.org](https://lists.debian.org/debian-security-announce/2026/msg00526.html)
- [ubuntu.com](https://ubuntu.com/security/notices/USN-8996-1)
- [CVE.org record CVE-2026-109518](https://www.cve.org/CVERecord?id=CVE-2026-109518)
- [NVD entry CVE-2026-109518](https://nvd.nist.gov/vuln/detail/CVE-2026-109518)
- [lists.debian.org](https://lists.debian.org/debian-lts-announce/2026/11/msg00004.html)
- [openwall.com](http://www.openwall.com/lists/oss-security/2026/11/04/12)

---
Source page: https://erroneo.us/security/cve/CVE-2026-109518/ · Security Digest: https://erroneo.us/security/ · More: https://erroneo.us/llms.txt