SUSE-SU-2026:23884-1

This update for util-linux fixes the following issues:

• CVE-2026-13595: heap use-after-free in libblkid nested partition probing (bsc#1269583).
• CVE-2026-27456: TOCTOU in the mount program when setting up loop devices (bsc#1261606).
• CVE-2026-53612: local privilege escalation via TOCTOU in mount(8) hook_owner.c chmod/chown (bsc#1268886).
• CVE-2026-53613: local privilege escalation via TOCTOU in mount(8) - Target Path Redirection (bsc#1268886).
• CVE-2026-53614: local privilege escalation via LIBMOUNT_FORCE_MOUNT2 Environment Variable - nosuid/noexec Bypass in SUID mount(8) (bsc#1268886).
• CVE-2026-76642: failed external mount helper triggers privileged X-mount post-hooks, which enables local privilege escalation (bsc#1278349).
• CVE-2026-78408: nsenter --join-cgroup leaks root cgroup migration authority, which allows for migration or termination of root processes (bsc#1278348).
• CVE-2026-78410: restricted bind mounts do not pin the source, which allows for X-mount.owner/group/mode redirection (bsc#1278347).

Changes for util-linux:

• lib/fileutils: add ul_openat_resolve() openat2 wrapper (bsc#1275441)
• lib/fileutils: fix RESOLVE_NO_SYMLINKS fallback value
• lib/fileutils: fix unused parameter warnings without SYS_openat2
• libmount: add missing fileutils.h include to hook_idmap.c
• libmount: add mnt_open_tree() helper for safe tree opening
• libmount: pin source path with openat2() for restricted users (bsc#1275441, bsc#1278347, CVE-2026-78410)
• libmount: restrict source path canonicalization for non-root users (bsc#1275441, bsc#1278347, CVE-2026-78410)
• libmount: skip post-mount hooks after failed mount helper (bsc#1275441, bsc#1278349, CVE-2026-76642)
• libmount: use USE_LIBMOUNT_MOUNTFD_SUPPORT for idmap hook
• nsenter: close cgroup.procs fd after join to prevent authority leak (bsc#1275441, bsc#1278348, CVE-2026-78408)
• nsenter, unshare: add O_CLOEXEC to all open() calls (bsc#1275441, bsc#1278348, CVE-2026-78408)
• wall, write: sanitize hostname in banner header (bsc#1275441)
• Add missing function. (bsc#1275441)
• ipcutils: Prevent using uninitialized variable (bsc#1268886)
• BREAKING CHANGE: Paths must always be canonicalized for unprivileged users to ensure safe target resolution. X-mount.nocanonicalize is ignored for them.
• INCOMAPTIBLE CHANGE (linux < 6.15): X-mount.subdir: The safe detached subdirectory is no more supported for unprivileged users for safety reasons.
• liblastlog2: Wait on busy SQLite connections (bsc#1268886).
• libmount: Fix subvolid buffer overflow in get_btrfs_fs_root (bsc#1268886).
• libblkid: Fix use-after-free in nested partition probing (bsc#1269583, bsc#1268886, CVE-2026-13595)
• libmount: fix SUID bypass via LIBMOUNT_FORCE_MOUNT2 and legacy mount path (bsc#1268886, CVE-2026-53614, GHSA-67r7-8m5w-22wx).
• fileutils: add ul_open_no_symlinks() needed by other patches (bsc#1268886).
• libmount: add fd_target to context for TOCTOU race condition prevention (bsc#1268886, CVE-2026-53613, GHSA-8gj5-72r3-428g).
• libmount: ignore X-mount.nocanonicalize for restricted users
• libmount: use fd-based fchownat/chmod in hook_owner (bsc#1268886, CVE-2026-53612, GHSA-g8wm-75wr-g2vh).
• libmount: restrict X-mount.subdir for non-root (bsc#1268886).
• libmount: use fd_target in hook_idmap for move_mount()
• libmount: add mount ID verification and man page TOCTOU note
• loopdev: use openat2(RESOLVE_NO_SYMLINKS) for backing file (bsc#1268886#c2, bsc#1261606).
• Ignore pam-config error that prevents update failure if common* pam configuration is not symlink to common-*-pc (bsc#1270219).