ALAS2027-2026-205

References: CVE-2026-78408  CVE-2026-78410  CVE-2026-76642 
FAQs regarding Amazon Linux ALAS/CVE Severity

Issue Overview:

Package updates are available for Amazon Linux 2027 that fix the following vulnerabilities:
CVE-2026-78410:
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-2026-78408:
The nsenter --join-cgroup option opens the target cgroup.procs file as root and leaves that file descriptor open across later namespace and credential changes and across execve(). Because the kernel checks later cgroup migrations using the credentials from the original open, a program run in an attacker-controlled target can inherit root's ability to move host processes between cgroups. After a privileged operator uses --join-cgroup against that target, an unprivileged user can migrate and terminate unrelated root processes.

CVE-2026-76642:
A flaw was found in util-linux. When an external mount.<type> helper runs but exits with a nonzero status, libmount still treats the helper invocation as successful and runs privileged post-mount hooks. A local unprivileged user with an /etc/fstab entry that uses the user option together with X-mount.idmap or X-mount.owner/group/mode can cause those hooks to clone or re-own the underlying filesystem after the helper fails, leading to local privilege escalation.

Issue Correction:
Run dnf update util-linux --releasever 2027.0.20261012 or dnf update --advisory ALAS2027-2026-205 --releasever 2027.0.20261012 to update your system.

New Packages:

aarch64:
    libuuid-2.42.4-1.amzn2027.aarch64
    libfdisk-devel-2.42.4-1.amzn2027.aarch64
    libsmartcols-devel-2.42.4-1.amzn2027.aarch64
    util-linux-core-debuginfo-2.42.4-1.amzn2027.aarch64
    util-linux-2.42.4-1.amzn2027.aarch64
    libmount-debuginfo-2.42.4-1.amzn2027.aarch64
    util-linux-i18n-2.42.4-1.amzn2027.aarch64
    python3-libmount-2.42.4-1.amzn2027.aarch64
    libsmartcols-debuginfo-2.42.4-1.amzn2027.aarch64
    liblastlog2-debuginfo-2.42.4-1.amzn2027.aarch64
    liblastlog2-2.42.4-1.amzn2027.aarch64
    libblkid-2.42.4-1.amzn2027.aarch64
    util-linux-script-2.42.4-1.amzn2027.aarch64
    util-linux-debugsource-2.42.4-1.amzn2027.aarch64
    liblastlog2-devel-2.42.4-1.amzn2027.aarch64
    util-linux-core-2.42.4-1.amzn2027.aarch64
    libsmartcols-2.42.4-1.amzn2027.aarch64
    libfdisk-2.42.4-1.amzn2027.aarch64
    libmount-2.42.4-1.amzn2027.aarch64
    util-linux-script-debuginfo-2.42.4-1.amzn2027.aarch64
    libmount-devel-2.42.4-1.amzn2027.aarch64
    uuidd-debuginfo-2.42.4-1.amzn2027.aarch64
    uuidd-2.42.4-1.amzn2027.aarch64
    python3-libmount-debuginfo-2.42.4-1.amzn2027.aarch64
    libblkid-debuginfo-2.42.4-1.amzn2027.aarch64
    libblkid-devel-2.42.4-1.amzn2027.aarch64
    util-linux-debuginfo-2.42.4-1.amzn2027.aarch64
    libuuid-devel-2.42.4-1.amzn2027.aarch64
    libfdisk-debuginfo-2.42.4-1.amzn2027.aarch64
    libuuid-debuginfo-2.42.4-1.amzn2027.aarch64

src:
    util-linux-2.42.4-1.amzn2027.src

x86_64:
    libfdisk-debuginfo-2.42.4-1.amzn2027.x86_64
    liblastlog2-2.42.4-1.amzn2027.x86_64
    libmount-devel-2.42.4-1.amzn2027.x86_64
    libmount-debuginfo-2.42.4-1.amzn2027.x86_64
    libblkid-debuginfo-2.42.4-1.amzn2027.x86_64
    libfdisk-devel-2.42.4-1.amzn2027.x86_64
    libuuid-debuginfo-2.42.4-1.amzn2027.x86_64
    util-linux-script-debuginfo-2.42.4-1.amzn2027.x86_64
    util-linux-i18n-2.42.4-1.amzn2027.x86_64
    uuidd-debuginfo-2.42.4-1.amzn2027.x86_64
    util-linux-core-2.42.4-1.amzn2027.x86_64
    libsmartcols-devel-2.42.4-1.amzn2027.x86_64
    util-linux-debugsource-2.42.4-1.amzn2027.x86_64
    liblastlog2-devel-2.42.4-1.amzn2027.x86_64
    util-linux-debuginfo-2.42.4-1.amzn2027.x86_64
    util-linux-script-2.42.4-1.amzn2027.x86_64
    libblkid-devel-2.42.4-1.amzn2027.x86_64
    python3-libmount-debuginfo-2.42.4-1.amzn2027.x86_64
    libsmartcols-debuginfo-2.42.4-1.amzn2027.x86_64
    libblkid-2.42.4-1.amzn2027.x86_64
    libuuid-2.42.4-1.amzn2027.x86_64
    liblastlog2-debuginfo-2.42.4-1.amzn2027.x86_64
    uuidd-2.42.4-1.amzn2027.x86_64
    libfdisk-2.42.4-1.amzn2027.x86_64
    util-linux-core-debuginfo-2.42.4-1.amzn2027.x86_64
    python3-libmount-2.42.4-1.amzn2027.x86_64
    libuuid-devel-2.42.4-1.amzn2027.x86_64
    libsmartcols-2.42.4-1.amzn2027.x86_64
    libmount-2.42.4-1.amzn2027.x86_64
    util-linux-2.42.4-1.amzn2027.x86_64