RHSA-2026:39082 - Security Advisory

Topic

An update for kernel-rt is now available for Red Hat Enterprise Linux 8.

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-rt packages provide the Real Time Linux Kernel, which enables fine-tuning for systems with extremely high determinism requirements.

Security Fix(es):

• kernel: net/sched: ets: Always remove class from active list before deleting in ets_qdisc_change (CVE-2025-71066)
• kernel: iommu: disable SVA when CONFIG_X86 is set (CVE-2025-71089)
• kernel: net: atm: fix crash due to unvalidated vcc pointer in sigd_send() (CVE-2026-31411)
• kernel: rtmutex: Use waiter::task instead of current in remove_waiter() (CVE-2026-43499)
• kernel: KVM: x86: Fix shadow paging use-after-free due to unexpected GFN (CVE-2026-46113)
• kernel: Linux kernel: netfilter: ebtables SNAT target writes to shared memory pages during ARP hardware address rewrite (CVE-2026-53266)
• kernel: futex/requeue: Prevent NULL pointer dereference in remove_waiter() on self-deadlock (CVE-2026-53166)
• kernel: KVM: x86: Fix shadow paging use-after-free due to unexpected role (CVE-2026-53359)

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 Real Time 8 x86_64
• Red Hat Enterprise Linux for Real Time for NFV 8 x86_64
• Red Hat Enterprise Linux for x86_64 - Extended Life Cycle 8.10 x86_64

Fixes

• BZ - 2429036 - CVE-2025-71066 kernel: net/sched: ets: Always remove class from active list before deleting in ets_qdisc_change
• BZ - 2429104 - CVE-2025-71089 kernel: iommu: disable SVA when CONFIG_X86 is set
• BZ - 2456521 - CVE-2026-31411 kernel: net: atm: fix crash due to unvalidated vcc pointer in sigd_send()
• BZ - 2480453 - CVE-2026-43499 kernel: rtmutex: Use waiter::task instead of current in remove_waiter()
• BZ - 2482587 - CVE-2026-46113 kernel: KVM: x86: Fix shadow paging use-after-free due to unexpected GFN
• BZ - 2485368 - CVE-2026-53266 kernel: Linux kernel: netfilter: ebtables SNAT target writes to shared memory pages during ARP hardware address rewrite
• BZ - 2492805 - CVE-2026-53166 kernel: futex/requeue: Prevent NULL pointer dereference in remove_waiter() on self-deadlock
• BZ - 2497033 - CVE-2026-53359 kernel: KVM: x86: Fix shadow paging use-after-free due to unexpected role

CVEs

• CVE-2025-71066
• CVE-2025-71089
• CVE-2026-31411
• CVE-2026-43499
• CVE-2026-46113
• CVE-2026-53166
• CVE-2026-53266
• CVE-2026-53359

References

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