RHSA-2026:25120 - 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 Critical. 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: geneve: Fix use-after-free in geneve_find_dev(). (CVE-2025-21858)
• kernel: smc: Fix use-after-free in tcp_write_timer_handler() (CVE-2023-53781)
• kernel: nbd: defer config unlock in nbd_genl_connect (CVE-2025-68366)
• kernel: libceph: prevent potential out-of-bounds reads in handle_auth_done() (CVE-2026-22984)
• kernel: libceph: replace overzealous BUG_ON in osdmap_apply_incremental() (CVE-2026-22990)
• kernel: netfilter: nf_tables: release flowtable after rcu grace period on error (CVE-2026-23392)
• kernel: ALSA: 6fire: fix use-after-free on disconnect (CVE-2026-31581)
• kernel: smb: client: fix OOB reads parsing symlink error response (CVE-2026-31613)
• kernel: ip6_tunnel: clear skb2->cb[] in ip4ip6_err() (CVE-2026-43037)
• kernel: ipv6: icmp: clear skb2->cb[] in ip6_err_gen_icmpv6_unreach() (CVE-2026-43038)
• kernel: dlm: validate length in dlm_search_rsb_tree (CVE-2026-43125)
• kernel: RDMA/rxe: Fix double free in rxe_srq_from_init (CVE-2026-45852)
• kernel: RDMA/mlx4: Fix mis-use of RCU in mlx4_srq_event() (CVE-2026-46181)

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.

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 - 2351619 - CVE-2025-21858 kernel: geneve: Fix use-after-free in geneve_find_dev().
• BZ - 2420279 - CVE-2023-53781 kernel: smc: Fix use-after-free in tcp_write_timer_handler()
• BZ - 2424881 - CVE-2025-68366 kernel: nbd: defer config unlock in nbd_genl_connect
• BZ - 2432389 - CVE-2026-22984 kernel: libceph: prevent potential out-of-bounds reads in handle_auth_done()
• BZ - 2432400 - CVE-2026-22990 kernel: libceph: replace overzealous BUG_ON in osdmap_apply_incremental()
• BZ - 2451218 - CVE-2026-23392 kernel: netfilter: nf_tables: release flowtable after rcu grace period on error
• BZ - 2461471 - CVE-2026-31581 kernel: ALSA: 6fire: fix use-after-free on disconnect
• BZ - 2461480 - CVE-2026-31613 kernel: smb: client: fix OOB reads parsing symlink error response
• BZ - 2464351 - CVE-2026-43037 kernel: ip6_tunnel: clear skb2->cb[] in ip4ip6_err()
• BZ - 2464397 - CVE-2026-43038 kernel: ipv6: icmp: clear skb2->cb[] in ip6_err_gen_icmpv6_unreach()
• BZ - 2467234 - CVE-2026-43125 kernel: dlm: validate length in dlm_search_rsb_tree
• BZ - 2482166 - CVE-2026-45852 kernel: RDMA/rxe: Fix double free in rxe_srq_from_init
• BZ - 2482532 - CVE-2026-46181 kernel: RDMA/mlx4: Fix mis-use of RCU in mlx4_srq_event()

CVEs

• CVE-2023-53781
• CVE-2025-21858
• CVE-2025-68366
• CVE-2026-22984
• CVE-2026-22990
• CVE-2026-23392
• CVE-2026-31581
• CVE-2026-31613
• CVE-2026-43037
• CVE-2026-43038
• CVE-2026-43125
• CVE-2026-45852
• CVE-2026-46181

References

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