CVE-2026-84042 Crun: crun: rootful krun with passt executes container payload as host root
Attackers can execute container payloads with host root privileges when using crun with libkrun and passt networking, requiring immediate upgrade.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-84042?
CVE-2026-84042 is a high-severity vulnerability in Red Hat Enterprise Linux 10, published on 10 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
A flaw was found in crun. When crun is built with libkrun and a container is started rootful with passt networking (krun.use_passt), crun can execute attacker-controlled payload from the container image with host root privileges. The issue is a regression in crun 1.29. It affects crun >= 1.29
Weakness: CWE-269
Which versions are affected by CVE-2026-84042?
How do I fix CVE-2026-84042?
Upgrade to a fixed version.
Is CVE-2026-84042 being exploited?
There is no known exploitation of CVE-2026-84042 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-84042, GHSA-ggww-wrxv-mmw2, UBUNTU-CVE-2026-84042.