RHSA-2023:4255HighCVSS 7.8

Red Hat Security Advisory: kernel-rt security and bug fix update

Published
July 25, 2023
Last Modified
July 30, 2026

🔗 CVE IDs covered (2)

CVE-2023-1281 →CVE-2023-32233 →

📋 Description

CVE-2023-1281 — kernel: tcindex: use-after-free vulnerability in traffic control index filter allows privilege escalation CVE-2023-32233 — kernel: netfilter: use-after-free in nf_tables when processing batch requests can lead to privilege escalation

🎯 Affected products49

  • Red Hat Enterprise Linux NFV E4S (v.8.4)
  • Red Hat Enterprise Linux NFV TUS (v.8.4)
  • Red Hat Enterprise Linux RT TUS (v.8.4)
  • kernel-rt-0:4.18.0-305.97.1.rt7.172.el8_4.src as a component of Red Hat Enterprise Linux NFV E4S (v.8.4)
  • kernel-rt-0:4.18.0-305.97.1.rt7.172.el8_4.src as a component of Red Hat Enterprise Linux NFV TUS (v.8.4)
  • kernel-rt-0:4.18.0-305.97.1.rt7.172.el8_4.src as a component of Red Hat Enterprise Linux RT TUS (v.8.4)
  • kernel-rt-0:4.18.0-305.97.1.rt7.172.el8_4.x86_64 as a component of Red Hat Enterprise Linux NFV E4S (v.8.4)
  • kernel-rt-0:4.18.0-305.97.1.rt7.172.el8_4.x86_64 as a component of Red Hat Enterprise Linux NFV TUS (v.8.4)
  • kernel-rt-0:4.18.0-305.97.1.rt7.172.el8_4.x86_64 as a component of Red Hat Enterprise Linux RT TUS (v.8.4)
  • kernel-rt-core-0:4.18.0-305.97.1.rt7.172.el8_4.x86_64 as a component of Red Hat Enterprise Linux NFV E4S (v.8.4)
  • kernel-rt-core-0:4.18.0-305.97.1.rt7.172.el8_4.x86_64 as a component of Red Hat Enterprise Linux NFV TUS (v.8.4)
  • kernel-rt-core-0:4.18.0-305.97.1.rt7.172.el8_4.x86_64 as a component of Red Hat Enterprise Linux RT TUS (v.8.4)
  • kernel-rt-debug-0:4.18.0-305.97.1.rt7.172.el8_4.x86_64 as a component of Red Hat Enterprise Linux NFV E4S (v.8.4)
  • kernel-rt-debug-0:4.18.0-305.97.1.rt7.172.el8_4.x86_64 as a component of Red Hat Enterprise Linux NFV TUS (v.8.4)
  • kernel-rt-debug-0:4.18.0-305.97.1.rt7.172.el8_4.x86_64 as a component of Red Hat Enterprise Linux RT TUS (v.8.4)
  • kernel-rt-debug-core-0:4.18.0-305.97.1.rt7.172.el8_4.x86_64 as a component of Red Hat Enterprise Linux NFV E4S (v.8.4)
  • kernel-rt-debug-core-0:4.18.0-305.97.1.rt7.172.el8_4.x86_64 as a component of Red Hat Enterprise Linux NFV TUS (v.8.4)
  • kernel-rt-debug-core-0:4.18.0-305.97.1.rt7.172.el8_4.x86_64 as a component of Red Hat Enterprise Linux RT TUS (v.8.4)
  • kernel-rt-debug-debuginfo-0:4.18.0-305.97.1.rt7.172.el8_4.x86_64 as a component of Red Hat Enterprise Linux NFV E4S (v.8.4)
  • kernel-rt-debug-debuginfo-0:4.18.0-305.97.1.rt7.172.el8_4.x86_64 as a component of Red Hat Enterprise Linux NFV TUS (v.8.4)
  • kernel-rt-debug-debuginfo-0:4.18.0-305.97.1.rt7.172.el8_4.x86_64 as a component of Red Hat Enterprise Linux RT TUS (v.8.4)
  • kernel-rt-debug-devel-0:4.18.0-305.97.1.rt7.172.el8_4.x86_64 as a component of Red Hat Enterprise Linux NFV E4S (v.8.4)
  • kernel-rt-debug-devel-0:4.18.0-305.97.1.rt7.172.el8_4.x86_64 as a component of Red Hat Enterprise Linux NFV TUS (v.8.4)
  • kernel-rt-debug-devel-0:4.18.0-305.97.1.rt7.172.el8_4.x86_64 as a component of Red Hat Enterprise Linux RT TUS (v.8.4)
  • kernel-rt-debug-kvm-0:4.18.0-305.97.1.rt7.172.el8_4.x86_64 as a component of Red Hat Enterprise Linux NFV E4S (v.8.4)
  • kernel-rt-debug-kvm-0:4.18.0-305.97.1.rt7.172.el8_4.x86_64 as a component of Red Hat Enterprise Linux NFV TUS (v.8.4)
  • kernel-rt-debug-modules-0:4.18.0-305.97.1.rt7.172.el8_4.x86_64 as a component of Red Hat Enterprise Linux NFV E4S (v.8.4)
  • kernel-rt-debug-modules-0:4.18.0-305.97.1.rt7.172.el8_4.x86_64 as a component of Red Hat Enterprise Linux NFV TUS (v.8.4)
  • kernel-rt-debug-modules-0:4.18.0-305.97.1.rt7.172.el8_4.x86_64 as a component of Red Hat Enterprise Linux RT TUS (v.8.4)
  • kernel-rt-debug-modules-extra-0:4.18.0-305.97.1.rt7.172.el8_4.x86_64 as a component of Red Hat Enterprise Linux NFV E4S (v.8.4)
  • +19 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: This flaw can be mitigated by preventing the affected traffic control index filter (cls_tcindex) kernel module from loading during the boot time, ensure the module is added into the blacklist file. ~~~ Refer: How do I blacklist a kernel module to prevent it from loading automatically? https://access.redhat.com/solutions/41278 ~~~ Workaround: 1. This flaw can be mitigated by preventing the affected netfilter (nf_tables) kernel module from being loaded. For instructions on how to blacklist a kernel module, please see https://access.redhat.com/solutions/41278. 2. If the module cannot be disabled, on non-containerized deployments of Red Hat Enterprise Linux, the mitigation is to disable user namespaces: ``` # echo "user.max_user_namespaces=0" > /etc/sysctl.d/userns.conf # sysctl -p /etc/sysctl.d/userns.conf ``` On containerized deployments, such as Red Hat OpenShift Container Platform, do not use the second mitigation (disabling user namespaces) as the functionality is needed to be enabled. The first mitigation (blacklisting nf_tables) is still viable for containerized deployments, providing the environment is not using netfilter.

🔗 References (5)