RHSA-2026:55765 - 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: mm/slub: avoid accessing metadata when pointer is invalid in object_err() (CVE-2025-39902)
• kernel: drm/amdkfd: Fix out-of-bounds write in kfd_event_page_set() (CVE-2026-43206)
• kernel: crypto: ccp - copy IV using skcipher ivsize (CVE-2026-53016)
• kernel: drm/amd/display: Clamp VBIOS HDMI retimer register count to array size (CVE-2026-53136)
• kernel: drm/amd/display: Use krealloc_array() in dal_vector_reserve() (CVE-2026-53329)
• kernel: drm/amdgpu: zero-initialize GART table on allocation (CVE-2026-53374)
• kernel: drm/i915: Fix potential UAF in TTM object purge (CVE-2026-63884)
• kernel: drm/amdgpu: fix amdgpu_hmm_range_get_pages (CVE-2026-63879)
• kernel: drm/amd/display: Validate payload length and link_index in dc_process_dmub_aux_transfer_async (CVE-2026-64219)
• kernel: can:bcm: arbitrary kernel code execution leading to escalate privileges (CVE-2026-17523)

Bug Fix(es) and Enhancement(s):

• Backport "sched/deadline: Fix bandwidth reclaim equation in GRUB" to RHEL 8.10 (JIRA:RHEL-189997)
• vhost: reset the vring metadata cache on vring reconfiguration [rhel-8.10.z] (JIRA:RHEL-224556)

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 - 2400594 - CVE-2025-39902 kernel: mm/slub: avoid accessing metadata when pointer is invalid in object_err()
• BZ - 2467156 - CVE-2026-43206 kernel: drm/amdkfd: Fix out-of-bounds write in kfd_event_page_set()
• BZ - 2492269 - CVE-2026-53016 kernel: crypto: ccp - copy IV using skcipher ivsize
• BZ - 2492768 - CVE-2026-53136 kernel: drm/amd/display: Clamp VBIOS HDMI retimer register count to array size
• BZ - 2495941 - CVE-2026-53329 kernel: drm/amd/display: Use krealloc_array() in dal_vector_reserve()
• BZ - 2502188 - CVE-2026-53374 kernel: drm/amdgpu: zero-initialize GART table on allocation
• BZ - 2502321 - CVE-2026-63884 kernel: drm/i915: Fix potential UAF in TTM object purge
• BZ - 2502463 - CVE-2026-63879 kernel: drm/amdgpu: fix amdgpu_hmm_range_get_pages
• BZ - 2506790 - CVE-2026-64219 kernel: drm/amd/display: Validate payload length and link_index in dc_process_dmub_aux_transfer_async
• BZ - 2507407 - CVE-2026-17523 kernel: can:bcm: arbitrary kernel code execution leading to escalate privileges

CVEs

• CVE-2025-39902
• CVE-2026-17523
• CVE-2026-43206
• CVE-2026-53016
• CVE-2026-53136
• CVE-2026-53329
• CVE-2026-53374
• CVE-2026-63879
• CVE-2026-63884
• CVE-2026-64219

References

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