CVE-2026-76642 util-linux libmount Privilege Escalation via Failed Mount Helper
Unprivileged users can escalate privileges by exploiting mount helper failures to modify filesystem permissions or inherit suid bits.
- 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-2026-76642?
CVE-2026-76642 is a high-severity vulnerability in util-linux, published on 3 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
util-linux versions through 2.41.5 and 2.42.2 fail to check mount helper exit status before running post-mount hooks, allowing unprivileged users to execute privileged operations on pre-existing filesystems. Attackers can exploit X-mount.idmap or X-mount.owner hooks to clone filesystems with inherited suid bits or modify target inode permissions after a helper fails, achieving privilege escalation.
Weakness: CWE-390
Which versions are affected by CVE-2026-76642?
How do I fix CVE-2026-76642?
Apply the vendor's patch.
Is CVE-2026-76642 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-76642 exists.
Sources
Also known as ALPINE-CVE-2026-76642, AZL-99081, BELL-CVE-2026-76642, DEBIAN-CVE-2026-76642, ECHO-b20e-705a-6d36, GHSA-m25x-3hj9-m26f and 5 more.