CVE-2026-53614

util-linux is a random collection of Linux utilities. In util-linux 2.39.1 through 2.41.4 and 2.42 through 2.42.1, the SUID mount utility reads the attacker-controlled LIBMOUNT_FORCE_MOUNT2 environment variable with getenv(), allowing a local low-privileged user to force the non-atomic legacy bind-mount path. With an /etc/fstab bind mount authorized by user or users and protected by nosuid, noexec, or nodev, an attacker can race the window between the initial bind mount and the remount that applies those security flags and execute a SUID program from the temporarily unprotected mount, 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 2.39.1 through 2.41.4 and 2.42 through 2.42.1, the SUID mount utility reads the attacker-controlled LIBMOUNT_FORCE_MOUNT2 environment variable with getenv(), allowing a local low-privileged user to force the non-atomic legacy bind-mount path. With an /etc/fstab bind mount authorized by user or users and protected by nosuid, noexec, or nodev, an attacker can race the window between the initial bind mount and the remount that applies those security flags and execute a SUID program from the temporarily unprotected mount, 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 2.39.1 through 2.41.4 and 2.42 through 2.42.1, the SUID mount utility reads the attacker-controlled LIBMOUNT_FORCE_MOUNT2 environment variable with getenv(), allowing a local low-privileged user to force the non-atomic legacy bind-mount path. With an /etc/fstab bind mount authorized by user or users and protected by nosuid, noexec, or nodev, an attacker can race the window between the initial bind mount and the remount that applies those security flags and execute a SUID program from the temporarily unprotected mount, 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)