RHSA-2026:56573 - Security Advisory

Topic

An update for kernel is now available for Red Hat Enterprise Linux 9.4 Update Services for SAP Solutions.

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: net: atm: fix crash due to unvalidated vcc pointer in sigd_send() (CVE-2026-31411)
• kernel: fs/smb/client: fix out-of-bounds read in cifs_sanitize_prepath (CVE-2026-43112)
• kernel: xen: AMD Zen 2 Processors: Privilege escalation via improper CPU cache isolation (CVE-2025-54518)

Bug Fix(es) and Enhancement(s):

• RHEL9.4 - s390/pci: Fix __pcilg_mio_inuser() inline assembly [rhel-9.4.z] (JIRA:RHEL-161489)

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 Server - AUS 9.4 x86_64
• Red Hat Enterprise Linux Server for Power LE - Update Services for SAP Solutions 9.4 ppc64le
• Red Hat Enterprise Linux for x86_64 - Update Services for SAP Solutions 9.4 x86_64
• Red Hat Enterprise Linux for ARM 64 - 4 years of updates 9.4 aarch64
• Red Hat Enterprise Linux for IBM z Systems - 4 years of updates 9.4 s390x
• Red Hat Enterprise Linux for x86_64 - Extended Life Cycle 9.4 x86_64
• Red Hat Enterprise Linux for ARM 64 - Extended Life Cycle 9.4 aarch64
• Red Hat Enterprise Linux for Power, little endian - Extended Life Cycle 9.4 ppc64le
• Red Hat Enterprise Linux for IBM z Systems - Extended Life Cycle 9.4 s390x

Fixes

• BZ - 2456521 - CVE-2026-31411 kernel: net: atm: fix crash due to unvalidated vcc pointer in sigd_send()
• BZ - 2467015 - CVE-2026-43112 kernel: fs/smb/client: fix out-of-bounds read in cifs_sanitize_prepath
• BZ - 2477784 - CVE-2025-54518 kernel: xen: AMD Zen 2 Processors: Privilege escalation via improper CPU cache isolation

CVEs

• CVE-2025-54518
• CVE-2026-31411
• CVE-2026-43112

References

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