CVE-2026-53612

util-linux is a random collection of Linux utilities. In util-linux 2.39 through 2.41.4 and 2.42 through 2.42.1, the SUID mount utility's hook_owner.c post-mount hook performs path-based chmod() and lchown() operations on a previously validated mount target. A local low-privileged user authorized by an /etc/fstab entry with user or users and an X-mount.mode, X-mount.owner, or X-mount.group option can use renameat2(RENAME_EXCHANGE) to race a writable ancestor of the target and redirect the privileged ownership or mode change to a root-owned path, potentially gaining root privileges. This issue is fixed in 2.41.5 and 2.42.2.

The util-linux package contains a random collection of files that implements some low-level basic linux utilities.

Security Fix(es):

CVE-2026-53612 has no publicly disclosed vulnerability details yet. It is only indexed by the Snyk data source. Details are pending disclosure.(CVE-2026-53612)

When an /etc/fstab entry is configured with the user or users option, mount(8) validates the target path before performing the mount syscall, creating a Time-of-Check-Time-of-Use (TOCTOU) window. A local unprivileged user with write access to an ancestor directory of the mount target can swap that directory to redirect the mount to an arbitrary root-owned location, potentially escalating privileges to root.(CVE-2026-53613)

A flaw was found in util-linux. The mount(8) SUID binary does not sanitize the LIBMOUNT_FORCE_MOUNT2 environment variable before use. A local unprivileged user can set this variable to force mount(8) to use the legacy two-step mount(2) code path, which applies security restrictions such as nosuid and noexec after the mount is already active. During this window, an attacker can execute a SUID binary from the mounted filesystem, allowing local privilege escalation to root. Affected versions: util-linux v2.39.1 through v2.43-devel (current master).(CVE-2026-53614)

A flaw was found in util-linux. Restricted bind mounts take the source path from fstab but do not pin that source before the privileged mount. A local unprivileged user who can replace the authorized source or a writable ancestor can redirect SUID mount(8) to bind another host directory. If the fstab entry also sets X-mount.owner, X-mount.group, or X-mount.mode, root then changes ownership or mode on that redirected inode.(CVE-2026-78410)

The util-linux package contains a random collection of files that implements some low-level basic linux utilities.

Security Fix(es):

CVE-2026-53612 has no publicly disclosed vulnerability details yet. It is only indexed by the Snyk data source. Details are pending disclosure.(CVE-2026-53612)

When an /etc/fstab entry is configured with the user or users option, mount(8) validates the target path before performing the mount syscall, creating a Time-of-Check-Time-of-Use (TOCTOU) window. A local unprivileged user with write access to an ancestor directory of the mount target can swap that directory to redirect the mount to an arbitrary root-owned location, potentially escalating privileges to root.(CVE-2026-53613)

A flaw was found in util-linux. The mount(8) SUID binary does not sanitize the LIBMOUNT_FORCE_MOUNT2 environment variable before use. A local unprivileged user can set this variable to force mount(8) to use the legacy two-step mount(2) code path, which applies security restrictions such as nosuid and noexec after the mount is already active. During this window, an attacker can execute a SUID binary from the mounted filesystem, allowing local privilege escalation to root. Affected versions: util-linux v2.39.1 through v2.43-devel (current master).(CVE-2026-53614)

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.(CVE-2026-76642)

A flaw was found in util-linux. Restricted bind mounts take the source path from fstab but do not pin that source before the privileged mount. A local unprivileged user who can replace the authorized source or a writable ancestor can redirect SUID mount(8) to bind another host directory. If the fstab entry also sets X-mount.owner, X-mount.group, or X-mount.mode, root then changes ownership or mode on that redirected inode.(CVE-2026-78410)

The util-linux package contains a random collection of files that implements some low-level basic linux utilities.

Security Fix(es):

CVE-2026-53612 has no publicly disclosed vulnerability details yet. It is only indexed by the Snyk data source. Details are pending disclosure.(CVE-2026-53612)

When an /etc/fstab entry is configured with the user or users option, mount(8) validates the target path before performing the mount syscall, creating a Time-of-Check-Time-of-Use (TOCTOU) window. A local unprivileged user with write access to an ancestor directory of the mount target can swap that directory to redirect the mount to an arbitrary root-owned location, potentially escalating privileges to root.(CVE-2026-53613)

A flaw was found in util-linux. The mount(8) SUID binary does not sanitize the LIBMOUNT_FORCE_MOUNT2 environment variable before use. A local unprivileged user can set this variable to force mount(8) to use the legacy two-step mount(2) code path, which applies security restrictions such as nosuid and noexec after the mount is already active. During this window, an attacker can execute a SUID binary from the mounted filesystem, allowing local privilege escalation to root. Affected versions: util-linux v2.39.1 through v2.43-devel (current master).(CVE-2026-53614)

A flaw was found in util-linux. Restricted bind mounts take the source path from fstab but do not pin that source before the privileged mount. A local unprivileged user who can replace the authorized source or a writable ancestor can redirect SUID mount(8) to bind another host directory. If the fstab entry also sets X-mount.owner, X-mount.group, or X-mount.mode, root then changes ownership or mode on that redirected inode.(CVE-2026-78410)

The util-linux packages contain a large variety of low-level system utilities that are necessary for a Linux system to function. Among others, these include the fdisk configuration tool and the login program.

Security Fix(es):

• util-linux: TOCTOU in the mount program when setting up loop devices (CVE-2026-27456)

• util-linux: util-linux: heap use-after-free in libblkid nested partition probing (CVE-2026-13595)

• util-linux: TOCTOU in the mount program via ancestor directory swap on target path (CVE-2026-53613)

• util-linux: util-linux: TOCTOU in the mount program when applying post-mount ownership/mode changes (CVE-2026-53612)

• util-linux: util-linux: SUID mount(8) allows nosuid/noexec bypass via LIBMOUNT_FORCE_MOUNT2 (CVE-2026-53614)

• util-linux: util-linux: failed external mount helper still runs privileged X-mount post-hooks (CVE-2026-76642)

• util-linux: util-linux: nsenter --join-cgroup leaks root cgroup migration authority (CVE-2026-78408)

• util-linux: util-linux: restricted bind mounts do not pin the source, allowing X-mount.owner/group/mode redirection (CVE-2026-78410)

• util-linux: util-linux: Partition metadata compromise via integer overflow in DOS partition parser (CVE-2026-53615)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

util-linux is a random collection of Linux utilities. In util-linux 2.39 through 2.41.4 and 2.42 through 2.42.1, the SUID mount utility's hook_owner.c post-mount hook performs path-based chmod() and lchown() operations on a previously validated mount target. A local low-privileged user authorized by an /etc/fstab entry with user or users and an X-mount.mode, X-mount.owner, or X-mount.group option can use renameat2(RENAME_EXCHANGE) to race a writable ancestor of the target and redirect the privileged ownership or mode change to a root-owned path, potentially gaining root privileges. This issue is fixed in 2.41.5 and 2.42.2.

The util-linux packages contain a large variety of low-level system utilities that are necessary for a Linux system to function. Among others, these include the fdisk configuration tool and the login program.

Security Fix(es):

• util-linux: TOCTOU in the mount program when setting up loop devices (CVE-2026-27456)
• util-linux: util-linux: heap use-after-free in libblkid nested partition probing (CVE-2026-13595)
• util-linux: TOCTOU in the mount program via ancestor directory swap on target path (CVE-2026-53613)
• util-linux: util-linux: TOCTOU in the mount program when applying post-mount ownership/mode changes (CVE-2026-53612)
• util-linux: util-linux: SUID mount(8) allows nosuid/noexec bypass via LIBMOUNT_FORCE_MOUNT2 (CVE-2026-53614)
• util-linux: util-linux: failed external mount helper still runs privileged X-mount post-hooks (CVE-2026-76642)
• util-linux: util-linux: nsenter --join-cgroup leaks root cgroup migration authority (CVE-2026-78408)
• util-linux: util-linux: restricted bind mounts do not pin the source, allowing X-mount.owner/group/mode redirection (CVE-2026-78410)
• util-linux: util-linux: Partition metadata compromise via integer overflow in DOS partition parser (CVE-2026-53615)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

util-linux is a random collection of Linux utilities. In util-linux 2.39 through 2.41.4 and 2.42 through 2.42.1, the SUID mount utility's hook_owner.c post-mount hook performs path-based chmod() and lchown() operations on a previously validated mount target. A local low-privileged user authorized by an /etc/fstab entry with user or users and an X-mount.mode, X-mount.owner, or X-mount.group option can use renameat2(RENAME_EXCHANGE) to race a writable ancestor of the target and redirect the privileged ownership or mode change to a root-owned path, potentially gaining root privileges. This issue is fixed in 2.41.5 and 2.42.2.

Additional fix for CVE-2024-28085. Local Privilege Escalation via TOCTOU in mount(8) hook_owner.c chmod/chown. (CVE-2026-53612) Local Privilege Escalation via TOCTOU in mount(8) — Target Path Redirection. (CVE-2026-53613) Local Privilege Escalation via LIBMOUNT_FORCE_MOUNT2 Environment Variable — nosuid/noexec Bypass in SUID mount(8). (CVE-2026-53614) mount(8) post-mount hooks execute after helper failure. (CVE-2026-76642) nsenter(1), unshare(1) file descriptor leak. (CVE-2026-78408) mount(8) X-mount.subdir symlink escape. (CVE-2026-78409) mount(8) TOCTOU race on source path. (CVE-2026-78410)

These are all security issues fixed in the libblkid-devel-2.42.2-1.1 package on the GA media of openSUSE Tumbleweed.

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).

This update for util-linux fixes the following issues:

• CVE-2026-13595: heap use-after-free read in libblkid nested partition probing (bsc#1269583).
• CVE-2026-27456: TOCTOU race condition in the mount program when setting up loop devices (bsc#1261606).
• Several security issues in releases prior to v2.42.2 and v2.41.5 (bsc#1268886).

This update for util-linux fixes the following issues:

Security issues fixed:

• CVE-2026-13595: heap use-after-free read in libblkid nested partition probing (bsc#1269583).
• CVE-2026-27456: TOCTOU race condition in the mount program when setting up loop devices (bsc#1261606).
• Several security issues in releases prior to v2.42.2 and v2.41.5 (bsc#1268886).

Other updates and bugfixes:

• Ignore pam-config error that prevents update failure if common* pam configuration is not symlink to common-*-pc (bsc#1270219).

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).

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).

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).

This update for util-linux fixes the following issues:

• CVE-2026-13595: heap use-after-free read in libblkid nested partition probing (bsc#1269583).
• CVE-2026-27456: TOCTOU race condition in the mount program when setting up loop devices (bsc#1261606).
• Several security issues in releases prior to v2.42.2 and v2.41.5 (bsc#1268886).

This update for util-linux fixes the following issues:

• CVE-2026-13595: heap use-after-free read in libblkid nested partition probing (bsc#1269583).
• CVE-2026-27456: TOCTOU race condition in the mount program when setting up loop devices (bsc#1261606).
• Several security issues in releases prior to v2.42.2 and v2.41.5 (bsc#1268886).

It was discovered that libblkid in util-linux had a heap use-after-free vulnerability during nested partition probing. An attacker who could present a crafted block device image could possibly use this issue to obtain sensitive information or cause a denial of service. (CVE-2026-13595)

It was discovered that the mount utility in util-linux had a time-of-check- time-of-use vulnerability when setting up loop devices. A local attacker could possibly use this issue to obtain unauthorized read access to root- protected files and block devices. (CVE-2026-27456)

It was discovered that the login utility in util-linux improperly canonicalized hostnames when invoked with the -h option. A remote attacker could possibly use this issue to bypass host-based access control rules. This issue only affected Ubuntu 26.04 LTS. (CVE-2026-3184)

It was discovered that libmount in util-linux had a time-of-check-time-of- use vulnerability in its ownership hook. A local attacker could possibly use this issue to gain elevated privileges. This issue only affected Ubuntu 24.04 LTS and Ubuntu 26.04 LTS. (CVE-2026-53612)

It was discovered that libmount in util-linux had a time-of-check-time-of- use vulnerability that allowed target path redirection during mount operations. A local attacker could possibly use this issue to gain elevated privileges. (CVE-2026-53613)

It was discovered that libmount in util-linux improperly handled the LIBMOUNT_FORCE_MOUNT2 environment variable in the SUID mount utility. A local attacker could possibly use this issue to bypass nosuid and noexec mount options and gain elevated privileges. This issue only affected Ubuntu 24.04 LTS and Ubuntu 26.04 LTS. (CVE-2026-53614)

It was discovered that libblkid in util-linux had an integer overflow vulnerability when parsing DOS partition tables. An attacker who could present a crafted block device image could possibly use this issue to cause a denial of service. (CVE-2026-53615)