CVE-2026-76642

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.

References

• https://github.com/util-linux/util-linux
• https://github.com/util-linux/util-linux/blob/v2.42.2/libmount/src/context_mount.c#L476
• https://github.com/util-linux/util-linux/blob/v2.42.2/libmount/src/context_mount.c#L892
• https://github.com/util-linux/util-linux/commit/1d14676ea70003e9f5b2a6a76af0cadb1190411a
• https://github.com/util-linux/util-linux/commit/a15c00a9e545aa8b9cf6ec0f888ff6c7b3eaeedc