RHSA-2026:93461HighCVSS 8.0

Red Hat Security Advisory: util-linux security update

Published
November 2, 2026
Last Modified
November 2, 2026

🔗 CVE IDs covered (9)

CVE-2026-53612 →CVE-2026-53613 →CVE-2026-53615 →CVE-2026-78410 →CVE-2026-13595 →CVE-2026-27456 →CVE-2026-53614 →CVE-2026-76642 →CVE-2026-78408 →

📋 Description

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

🎯 Affected products180

  • Red Hat Enterprise Linux AppStream (v. 10)
  • Red Hat Enterprise Linux BaseOS (v. 10)
  • Red Hat Enterprise Linux CodeReady Linux Builder (v. 10)
  • libblkid-0:2.40.2-18.el10_2.20.aarch64 as a component of Red Hat Enterprise Linux BaseOS (v. 10)
  • libblkid-0:2.40.2-18.el10_2.20.ppc64le as a component of Red Hat Enterprise Linux BaseOS (v. 10)
  • libblkid-0:2.40.2-18.el10_2.20.s390x as a component of Red Hat Enterprise Linux BaseOS (v. 10)
  • libblkid-0:2.40.2-18.el10_2.20.x86_64 as a component of Red Hat Enterprise Linux BaseOS (v. 10)
  • libblkid-debuginfo-0:2.40.2-18.el10_2.20.aarch64 as a component of Red Hat Enterprise Linux AppStream (v. 10)
  • libblkid-debuginfo-0:2.40.2-18.el10_2.20.aarch64 as a component of Red Hat Enterprise Linux BaseOS (v. 10)
  • libblkid-debuginfo-0:2.40.2-18.el10_2.20.aarch64 as a component of Red Hat Enterprise Linux CodeReady Linux Builder (v. 10)
  • libblkid-debuginfo-0:2.40.2-18.el10_2.20.ppc64le as a component of Red Hat Enterprise Linux AppStream (v. 10)
  • libblkid-debuginfo-0:2.40.2-18.el10_2.20.ppc64le as a component of Red Hat Enterprise Linux BaseOS (v. 10)
  • libblkid-debuginfo-0:2.40.2-18.el10_2.20.ppc64le as a component of Red Hat Enterprise Linux CodeReady Linux Builder (v. 10)
  • libblkid-debuginfo-0:2.40.2-18.el10_2.20.s390x as a component of Red Hat Enterprise Linux AppStream (v. 10)
  • libblkid-debuginfo-0:2.40.2-18.el10_2.20.s390x as a component of Red Hat Enterprise Linux BaseOS (v. 10)
  • libblkid-debuginfo-0:2.40.2-18.el10_2.20.s390x as a component of Red Hat Enterprise Linux CodeReady Linux Builder (v. 10)
  • libblkid-debuginfo-0:2.40.2-18.el10_2.20.x86_64 as a component of Red Hat Enterprise Linux AppStream (v. 10)
  • libblkid-debuginfo-0:2.40.2-18.el10_2.20.x86_64 as a component of Red Hat Enterprise Linux BaseOS (v. 10)
  • libblkid-debuginfo-0:2.40.2-18.el10_2.20.x86_64 as a component of Red Hat Enterprise Linux CodeReady Linux Builder (v. 10)
  • libblkid-devel-0:2.40.2-18.el10_2.20.aarch64 as a component of Red Hat Enterprise Linux AppStream (v. 10)
  • libblkid-devel-0:2.40.2-18.el10_2.20.ppc64le as a component of Red Hat Enterprise Linux AppStream (v. 10)
  • libblkid-devel-0:2.40.2-18.el10_2.20.s390x as a component of Red Hat Enterprise Linux AppStream (v. 10)
  • libblkid-devel-0:2.40.2-18.el10_2.20.x86_64 as a component of Red Hat Enterprise Linux AppStream (v. 10)
  • libfdisk-0:2.40.2-18.el10_2.20.aarch64 as a component of Red Hat Enterprise Linux BaseOS (v. 10)
  • libfdisk-0:2.40.2-18.el10_2.20.ppc64le as a component of Red Hat Enterprise Linux BaseOS (v. 10)
  • libfdisk-0:2.40.2-18.el10_2.20.s390x as a component of Red Hat Enterprise Linux BaseOS (v. 10)
  • libfdisk-0:2.40.2-18.el10_2.20.x86_64 as a component of Red Hat Enterprise Linux BaseOS (v. 10)
  • libfdisk-debuginfo-0:2.40.2-18.el10_2.20.aarch64 as a component of Red Hat Enterprise Linux AppStream (v. 10)
  • libfdisk-debuginfo-0:2.40.2-18.el10_2.20.aarch64 as a component of Red Hat Enterprise Linux BaseOS (v. 10)
  • libfdisk-debuginfo-0:2.40.2-18.el10_2.20.aarch64 as a component of Red Hat Enterprise Linux CodeReady Linux Builder (v. 10)
  • +150 more not shown

✅ Remediation

For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 Workaround: Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability. Workaround: To mitigate this flaw, remove the 'user' option from any loop mounts in the /etc/fstab file or ensure the the source path points to a root-owned directory where unprivileged users do not have write permissions. Workaround: In SUID/restricted mode, reject X-mount.mode= values containing SUID/SGID bits (04000/02000). Verify mount target path ancestor chain integrity before post-hook execution. Workaround: Review /etc/fstab and remove the user or users mount option from any entry where unprivileged user mounting is not strictly required. This eliminates the prerequisite for exploitation. For entries that must retain user mount capability, ensure all ancestor directories in the mount target path are owned by root and not writable by unprivileged users (mode 0755 or stricter), preventing the renameat2(RENAME_EXCHANGE) directory swap needed to exploit the race. These changes take effect immediately with no reboot required. Workaround: In the legacy bind path, use mount_setattr() to apply security flags atomically, eliminating the window between the two syscalls. Add SUID regression test: LIBMOUNT_FORCE_MOUNT2=always must not change API path selection for unprivileged callers. Workaround: Red Hat is not aware of a practical temporary workaround that fully mitigates this issue or meets Red Hat Product Security's standards for usability, deployment, applicability, or stability. Customers are advised to apply the relevant security updates when/if they become available. Workaround: Avoid combining the user (or users) fstab option with X-mount.idmap or X-mount.owner/group/mode on entries that invoke an external mount.<type> helper. Administrators can also remove or restrict user-mountable fstab entries that specify those X-mount.* options. Workaround: Upgrade to util-linux v2.41.6, v2.42.3, or later. Until a fix is applied, do not run nsenter --join-cgroup (including nsenter --target PID --all --join-cgroup) against untrusted processes or namespaces. The fix closes the cgroup.procs descriptor immediately after joining, and opens it with O_CLOEXEC. Workaround: Upgrade to util-linux v2.41.6, v2.42.3, or later. Until a fix is applied, do not allow unprivileged /etc/fstab bind or rbind entries that also specify X-mount.owner, X-mount.group, or X-mount.mode, especially when the bind source is below a user-writable ancestor.

🔗 References (12)