RHSA-2026:53989 - Security Advisory

Topic

An update for kernel is now available for Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support and Red Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-On.

Red Hat Product Security has rated this update as having a security impact of Important. A Common Vulnerability Scoring System (CVSS) base score, which gives a detailed severity rating, is available for each vulnerability from the CVE link(s) in the References section.

Description

The kernel packages contain the Linux kernel, the core of any Linux operating system.

Security Fix(es):

• kernel: xen/privcmd: fix double free via VMA splitting (CVE-2026-31787)
• kernel: fs/smb/client: fix out-of-bounds read in cifs_sanitize_prepath (CVE-2026-43112)
• kernel: md/bitmap: fix GPF in write_page caused by resize race (CVE-2026-43163)
• kernel: xen: AMD Zen 2 Processors: Privilege escalation via improper CPU cache isolation (CVE-2025-54518)
• kernel: dm log: fix out-of-bounds write due to region_count overflow (CVE-2026-53059)

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.

Solution

For details on how to apply this update, which includes the changes described in this advisory, refer to:

https://access.redhat.com/articles/11258

The system must be rebooted for this update to take effect.

Red Hat recommends treating all kernel errata as security-relevant. Given the kernel's fundamental role, any bug has a higher chance of impacting system security, even if that impact only becomes clear after a fix is published. Therefore, Red Hat prioritizes delivering fixes that improve our customers' overall security posture.

Because of this proactive approach, a patch may be associated with a CVE assignment at a future date. Retroactive CVE assignments are always documented in the corresponding errata and on Red Hat's CVE pages. We strongly advise against delaying updates, as doing so may leave your system exposed when protections are already available.

Affected Products

• Red Hat Enterprise Linux for x86_64 - Extended Life Cycle Long Life 8.6 x86_64
• Red Hat Enterprise Linux Server - AUS 8.6 x86_64

Fixes

• BZ - 2464092 - CVE-2026-31787 kernel: xen/privcmd: fix double free via VMA splitting
• BZ - 2467015 - CVE-2026-43112 kernel: fs/smb/client: fix out-of-bounds read in cifs_sanitize_prepath
• BZ - 2467059 - CVE-2026-43163 kernel: md/bitmap: fix GPF in write_page caused by resize race
• BZ - 2477784 - CVE-2025-54518 kernel: xen: AMD Zen 2 Processors: Privilege escalation via improper CPU cache isolation
• BZ - 2492277 - CVE-2026-53059 kernel: dm log: fix out-of-bounds write due to region_count overflow

CVEs

• CVE-2025-54518
• CVE-2026-31787
• CVE-2026-43112
• CVE-2026-43163
• CVE-2026-53059

References

• https://access.redhat.com/security/updates/classification/#important