CVE-2026-78409 Util-linux: util-linux: x-mount.subdir detached-tree resolution can escape via intermediate symlinks

The X-mount.subdir option uses a detached-tree fast path on Linux 6.15 and later and passes the configured subdirectory to opentree with ATSYMLINKNOFOLLOW. That flag does not stop intermediate symlink traversal or keep resolution inside the newly mounted filesystem. A local unprivileged user with...

CVE-2026-78409

A flaw in util-linux 's X-mount.subdir mount option allows a local unprivileged user to escape the intended subdirectory and attach an arbitrary host path at the intended mountpoint. On Linux 6.15 and later , the option takes a detached-tree fast path that calls open_tree() with AT_SYMLINK_NOFOLL...

USN-2798-1 linux-lts-vivid vulnerabilities

It was discovered that in certain situations, a directory could be renamed outside of a bind mounted location. An attacker could use this to escape bind mount containment and gain access to sensitive information. CVE-2015-2925 Moein Ghasemzadeh discovered that the USB WhiteHEAT serial driver...

USN-2797-1 linux-lts-utopic vulnerabilities

It was discovered that the Linux kernel did not check if a new IPv6 MTU set by a user space application was valid. A remote attacker could forge a route advertisement with an invalid MTU that a user space daemon like NetworkManager would honor and apply to the kernel, causing a denial of service...

USN-2794-1 linux vulnerabilities

It was discovered that in certain situations, a directory could be renamed outside of a bind mounted location. An attacker could use this to escape bind mount containment and gain access to sensitive information. CVE-2015-2925 Moein Ghasemzadeh discovered that the USB WhiteHEAT serial driver...