RHSA-2026:21745 - 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: Bluetooth: MGMT: Fix possible UAFs (CVE-2025-39981)
• kernel: ima: don't clear IMA_DIGSIG flag when setting or removing non-IMA xattr (CVE-2025-68183)
• kernel: ALSA: firewire-motu: fix buffer overflow in hwdep read for DSP events (CVE-2025-68347)
• kernel: libceph: make decode_pool() more resilient against corrupted osdmaps (CVE-2025-71116)
• kernel: Linux kernel: Denial of service and memory corruption in RDMA umad (CVE-2026-23243)
• kernel: Linux kernel: Use-after-free in traffic control (act_ct) may lead to denial of service or privilege escalation (CVE-2026-23270)
• kernel: netfilter: nf_conntrack_h323: check for zero length in DecodeQ931() (CVE-2026-23455)
• kernel: Bluetooth: SCO: Fix use-after-free in sco_recv_frame() due to missing sock_hold (CVE-2026-31408)
• kernel: can: raw: fix ro->uniq use-after-free in raw_rcv() (CVE-2026-31532)
• kernel: net: sched: act_csum: validate nested VLAN headers (CVE-2026-31684)
• kernel: netfilter: ip6t_eui64: reject invalid MAC header for all packets (CVE-2026-31685)
• kernel: netfilter: nf_conntrack_helper: pass helper to expect cleanup (CVE-2026-43027)
• kernel: Bluetooth: MGMT: validate LTK enc_size on load (CVE-2026-43020)
• kernel: HID: wacom: fix out-of-bounds read in wacom_intuos_bt_irq (CVE-2026-43051)
• kernel: smb: client: validate the whole DACL before rewriting it in cifsacl (CVE-2026-31709)
• kernel: md/bitmap: fix GPF in write_page caused by resize race (CVE-2026-43163)
• kernel: netfilter: xt_tcpmss: check remaining length before reading optlen (CVE-2026-43190)
• kernel: xfs: fix freemap adjustments when adding xattrs to leaf blocks (CVE-2026-43158)

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 - 2404105 - CVE-2025-39981 kernel: Bluetooth: MGMT: Fix possible UAFs
• BZ - 2422699 - CVE-2025-68183 kernel: ima: don't clear IMA_DIGSIG flag when setting or removing non-IMA xattr
• BZ - 2424879 - CVE-2025-68347 kernel: ALSA: firewire-motu: fix buffer overflow in hwdep read for DSP events
• BZ - 2429602 - CVE-2025-71116 kernel: libceph: make decode_pool() more resilient against corrupted osdmaps
• BZ - 2448594 - CVE-2026-23243 kernel: Linux kernel: Denial of service and memory corruption in RDMA umad
• BZ - 2448745 - CVE-2026-23270 kernel: Linux kernel: Use-after-free in traffic control (act_ct) may lead to denial of service or privilege escalation
• BZ - 2454810 - CVE-2026-23455 kernel: netfilter: nf_conntrack_h323: check for zero length in DecodeQ931()
• BZ - 2455334 - CVE-2026-31408 kernel: Bluetooth: SCO: Fix use-after-free in sco_recv_frame() due to missing sock_hold
• BZ - 2461107 - CVE-2026-31532 kernel: can: raw: fix ro->uniq use-after-free in raw_rcv()
• BZ - 2461757 - CVE-2026-31684 kernel: net: sched: act_csum: validate nested VLAN headers
• BZ - 2461759 - CVE-2026-31685 kernel: netfilter: ip6t_eui64: reject invalid MAC header for all packets
• BZ - 2464369 - CVE-2026-43027 kernel: netfilter: nf_conntrack_helper: pass helper to expect cleanup
• BZ - 2464455 - CVE-2026-43020 kernel: Bluetooth: MGMT: validate LTK enc_size on load
• BZ - 2464462 - CVE-2026-43051 kernel: HID: wacom: fix out-of-bounds read in wacom_intuos_bt_irq
• BZ - 2464476 - CVE-2026-31709 kernel: smb: client: validate the whole DACL before rewriting it in cifsacl
• BZ - 2467059 - CVE-2026-43163 kernel: md/bitmap: fix GPF in write_page caused by resize race
• BZ - 2467064 - CVE-2026-43190 kernel: netfilter: xt_tcpmss: check remaining length before reading optlen
• BZ - 2467210 - CVE-2026-43158 kernel: xfs: fix freemap adjustments when adding xattrs to leaf blocks

CVEs

• CVE-2025-39981
• CVE-2025-68183
• CVE-2025-68347
• CVE-2025-71116
• CVE-2026-23243
• CVE-2026-23270
• CVE-2026-23455
• CVE-2026-31408
• CVE-2026-31532
• CVE-2026-31684
• CVE-2026-31685
• CVE-2026-31709
• CVE-2026-43020
• CVE-2026-43027
• CVE-2026-43051
• CVE-2026-43158
• CVE-2026-43163
• CVE-2026-43190

References

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