RHSA-2026:22900HighCVSS 8.8

Red Hat Security Advisory: kernel-rt security update

Published
June 3, 2026
Last Modified
August 21, 2026

🔗 CVE IDs covered (7)

CVE-2025-39766 →CVE-2026-23270 →CVE-2026-31419 →CVE-2026-31709 →CVE-2026-43037 →CVE-2026-43038 →CVE-2026-43163 →

📋 Description

CVE-2025-39766 — kernel: net/sched: Make cake_enqueue return NET_XMIT_CN when past buffer_limit CVE-2026-23270 — kernel: Linux kernel: Use-after-free in traffic control (act_ct) may lead to denial of service or privilege escalation CVE-2026-31419 — kernel: Linux kernel: Use-after-free in bonding driver leads to denial of service CVE-2026-31709 — kernel: smb: client: validate the whole DACL before rewriting it in cifsacl CVE-2026-43037 — kernel: ip6_tunnel: clear skb2->cb[] in ip4ip6_err() CVE-2026-43038 — kernel: ipv6: icmp: clear skb2->cb[] in ip6_err_gen_icmpv6_unreach() CVE-2026-43163 — kernel: md/bitmap: fix GPF in write_page caused by resize race

🎯 Affected products36

  • Red Hat Enterprise Linux Real Time E4S (v.9.2)
  • Red Hat Enterprise Linux Real Time for NFV E4S (v.9.2)
  • kernel-rt-0:5.14.0-284.174.1.rt14.459.el9_2.src as a component of Red Hat Enterprise Linux Real Time E4S (v.9.2)
  • kernel-rt-0:5.14.0-284.174.1.rt14.459.el9_2.src as a component of Red Hat Enterprise Linux Real Time for NFV E4S (v.9.2)
  • kernel-rt-0:5.14.0-284.174.1.rt14.459.el9_2.x86_64 as a component of Red Hat Enterprise Linux Real Time E4S (v.9.2)
  • kernel-rt-0:5.14.0-284.174.1.rt14.459.el9_2.x86_64 as a component of Red Hat Enterprise Linux Real Time for NFV E4S (v.9.2)
  • kernel-rt-core-0:5.14.0-284.174.1.rt14.459.el9_2.x86_64 as a component of Red Hat Enterprise Linux Real Time E4S (v.9.2)
  • kernel-rt-core-0:5.14.0-284.174.1.rt14.459.el9_2.x86_64 as a component of Red Hat Enterprise Linux Real Time for NFV E4S (v.9.2)
  • kernel-rt-debug-0:5.14.0-284.174.1.rt14.459.el9_2.x86_64 as a component of Red Hat Enterprise Linux Real Time E4S (v.9.2)
  • kernel-rt-debug-0:5.14.0-284.174.1.rt14.459.el9_2.x86_64 as a component of Red Hat Enterprise Linux Real Time for NFV E4S (v.9.2)
  • kernel-rt-debug-core-0:5.14.0-284.174.1.rt14.459.el9_2.x86_64 as a component of Red Hat Enterprise Linux Real Time E4S (v.9.2)
  • kernel-rt-debug-core-0:5.14.0-284.174.1.rt14.459.el9_2.x86_64 as a component of Red Hat Enterprise Linux Real Time for NFV E4S (v.9.2)
  • kernel-rt-debug-debuginfo-0:5.14.0-284.174.1.rt14.459.el9_2.x86_64 as a component of Red Hat Enterprise Linux Real Time E4S (v.9.2)
  • kernel-rt-debug-debuginfo-0:5.14.0-284.174.1.rt14.459.el9_2.x86_64 as a component of Red Hat Enterprise Linux Real Time for NFV E4S (v.9.2)
  • kernel-rt-debug-devel-0:5.14.0-284.174.1.rt14.459.el9_2.x86_64 as a component of Red Hat Enterprise Linux Real Time E4S (v.9.2)
  • kernel-rt-debug-devel-0:5.14.0-284.174.1.rt14.459.el9_2.x86_64 as a component of Red Hat Enterprise Linux Real Time for NFV E4S (v.9.2)
  • kernel-rt-debug-kvm-0:5.14.0-284.174.1.rt14.459.el9_2.x86_64 as a component of Red Hat Enterprise Linux Real Time for NFV E4S (v.9.2)
  • kernel-rt-debug-modules-0:5.14.0-284.174.1.rt14.459.el9_2.x86_64 as a component of Red Hat Enterprise Linux Real Time E4S (v.9.2)
  • kernel-rt-debug-modules-0:5.14.0-284.174.1.rt14.459.el9_2.x86_64 as a component of Red Hat Enterprise Linux Real Time for NFV E4S (v.9.2)
  • kernel-rt-debug-modules-core-0:5.14.0-284.174.1.rt14.459.el9_2.x86_64 as a component of Red Hat Enterprise Linux Real Time E4S (v.9.2)
  • kernel-rt-debug-modules-core-0:5.14.0-284.174.1.rt14.459.el9_2.x86_64 as a component of Red Hat Enterprise Linux Real Time for NFV E4S (v.9.2)
  • kernel-rt-debug-modules-extra-0:5.14.0-284.174.1.rt14.459.el9_2.x86_64 as a component of Red Hat Enterprise Linux Real Time E4S (v.9.2)
  • kernel-rt-debug-modules-extra-0:5.14.0-284.174.1.rt14.459.el9_2.x86_64 as a component of Red Hat Enterprise Linux Real Time for NFV E4S (v.9.2)
  • kernel-rt-debuginfo-0:5.14.0-284.174.1.rt14.459.el9_2.x86_64 as a component of Red Hat Enterprise Linux Real Time E4S (v.9.2)
  • kernel-rt-debuginfo-0:5.14.0-284.174.1.rt14.459.el9_2.x86_64 as a component of Red Hat Enterprise Linux Real Time for NFV E4S (v.9.2)
  • kernel-rt-debuginfo-common-x86_64-0:5.14.0-284.174.1.rt14.459.el9_2.x86_64 as a component of Red Hat Enterprise Linux Real Time E4S (v.9.2)
  • kernel-rt-debuginfo-common-x86_64-0:5.14.0-284.174.1.rt14.459.el9_2.x86_64 as a component of Red Hat Enterprise Linux Real Time for NFV E4S (v.9.2)
  • kernel-rt-devel-0:5.14.0-284.174.1.rt14.459.el9_2.x86_64 as a component of Red Hat Enterprise Linux Real Time E4S (v.9.2)
  • kernel-rt-devel-0:5.14.0-284.174.1.rt14.459.el9_2.x86_64 as a component of Red Hat Enterprise Linux Real Time for NFV E4S (v.9.2)
  • kernel-rt-kvm-0:5.14.0-284.174.1.rt14.459.el9_2.x86_64 as a component of Red Hat Enterprise Linux Real Time for NFV E4S (v.9.2)
  • +6 more not shown

✅ Remediation

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. Workaround: To mitigate this issue, if SMB client functionality is not required, the `cifs` kernel module can be blacklisted to prevent it from loading. This can be achieved by creating a modprobe configuration file. 1. Create a file named `/etc/modprobe.d/disable-cifs.conf` with the following content: ``` install cifs /bin/true blacklist cifs ``` 2. Regenerate the initramfs to ensure the change takes effect on boot: ```bash dracut -f -v ``` or for systems using `mkinitrd`: ```bash mkinitrd -f /boot/initramfs-$(uname -r).img $(uname -r) ``` 3. A system reboot is required for the changes to take effect. Warning: Disabling the `cifs` module will prevent the system from mounting SMB/CIFS shares. Ensure this functionality is not critical before applying this mitigation. refer: https://access.redhat.com/solutions/4117281 Workaround: Mitigation for this issue is to skip loading the affected module `ip6_tunnel` onto the system till we have a fix available, this can be done by a blacklist mechanism, this will ensure the driver is not loaded at the boot time. ~~~ How do I blacklist a kernel module to prevent it from loading automatically? https://access.redhat.com/solutions/41278 ~~~ We may also want to detection and monitoring an affected system as below: ~~~ Monitor for exploitation attempts: # Enable kernel audit for IPv6 tunnel operations auditctl -a always,exit -F arch=b64 -S socket -F a0=10 -F a1=3 -k ipv6_tunnel # Monitor system logs for kernel panics/crashes journalctl -k -p err -f | grep -i "ip6_tunnel\|icmp\|stack" ~~~ Workaround: Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.

🔗 References (10)