CVE-2026-109518: Debian APT (High, CVSS 7.7)
- CVSS
- 7.7 High (v4.0)
- EPSS
- 0.9% chance of exploitation in the next 30 days (higher than 60.6% of CVEs)
- Exploited in the wild
- Not on CISA’s KEV list
- Public exploit
- Yes, reported in 3 GitHub repositories
- Weakness
- CWE-367, CWE-62
- Vector
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- Published
- Nov 4, 2026
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
Description from the National Vulnerability Database.
What to do
Check whether you run Debian APT, then apply the vendor’s fix or mitigation from the advisories below. Because this flaw is exploited or has public exploit code, treat it as urgent and check for signs of compromise, not just the patch level.
ThreatRoundup coverage
A Bad Mirror Can Hand You Root: Patch APT on Debian and Ubuntu
Sources: NVD, FIRST EPSS, CISA KEV, and public exploit databases (availability only). ThreatRoundup reports whether public exploit code exists but never links to it: fake proof-of-concepts that infect security researchers are common. This page updates automatically.