RHSA-2026:77634HighCVSS 8.8

Red Hat Security Advisory: kernel security, bug fix, and enhancement update

Published
October 8, 2026
Last Modified
October 31, 2026

🔗 CVE IDs covered (10)

CVE-2025-40237 →CVE-2026-43186 →CVE-2026-45991 →CVE-2026-64007 →CVE-2026-64383 →CVE-2026-64385 →CVE-2026-74705 →CVE-2026-52924 →CVE-2026-64386 →CVE-2026-80521 →

📋 Description

CVE-2025-40237 — kernel: fs/notify: call exportfs_encode_fid with s_umount CVE-2026-43186 — kernel: ipv6: ioam: fix heap buffer overflow in __ioam6_fill_trace_data() CVE-2026-45991 — kernel: udf: fix partition descriptor append bookkeeping CVE-2026-52924 — kernel: sctp: purge outqueue on stale COOKIE-ECHO handling CVE-2026-64007 — kernel: netfilter: synproxy: refresh tcphdr after skb_ensure_writable CVE-2026-64383 — kernel: smb: client: fix double-free in SMB2_flush() replay CVE-2026-64385 — kernel: Kernel SMB client: Double-free vulnerability allows remote denial of service or privilege escalation CVE-2026-64386 — kernel: smb: client: fix query_info() replay double-free CVE-2026-74705 — kernel: udp: fix potential use-after-free in tunnel segmentation CVE-2026-80521 — kernel: af_unix: Unlink scc_entry in unix_del_edge()

🎯 Affected products200

  • Red Hat Enterprise Linux AppStream EUS (v. 10.0)
  • Red Hat Enterprise Linux BaseOS EUS (v. 10.0)
  • Red Hat Enterprise Linux CodeReady Linux Builder EUS (v. 10.0)
  • Red Hat Enterprise Linux Real Time EUS (v. 10.0)
  • Red Hat Enterprise Linux Real Time for NFV EUS (v. 10.0)
  • kernel-0:6.12.0-55.109.1.el10_0.aarch64 as a component of Red Hat Enterprise Linux BaseOS EUS (v. 10.0)
  • kernel-0:6.12.0-55.109.1.el10_0.ppc64le as a component of Red Hat Enterprise Linux BaseOS EUS (v. 10.0)
  • kernel-0:6.12.0-55.109.1.el10_0.s390x as a component of Red Hat Enterprise Linux BaseOS EUS (v. 10.0)
  • kernel-0:6.12.0-55.109.1.el10_0.src as a component of Red Hat Enterprise Linux BaseOS EUS (v. 10.0)
  • kernel-0:6.12.0-55.109.1.el10_0.x86_64 as a component of Red Hat Enterprise Linux BaseOS EUS (v. 10.0)
  • kernel-64k-0:6.12.0-55.109.1.el10_0.aarch64 as a component of Red Hat Enterprise Linux BaseOS EUS (v. 10.0)
  • kernel-64k-core-0:6.12.0-55.109.1.el10_0.aarch64 as a component of Red Hat Enterprise Linux BaseOS EUS (v. 10.0)
  • kernel-64k-debug-0:6.12.0-55.109.1.el10_0.aarch64 as a component of Red Hat Enterprise Linux BaseOS EUS (v. 10.0)
  • kernel-64k-debug-core-0:6.12.0-55.109.1.el10_0.aarch64 as a component of Red Hat Enterprise Linux BaseOS EUS (v. 10.0)
  • kernel-64k-debug-debuginfo-0:6.12.0-55.109.1.el10_0.aarch64 as a component of Red Hat Enterprise Linux AppStream EUS (v. 10.0)
  • kernel-64k-debug-debuginfo-0:6.12.0-55.109.1.el10_0.aarch64 as a component of Red Hat Enterprise Linux BaseOS EUS (v. 10.0)
  • kernel-64k-debug-debuginfo-0:6.12.0-55.109.1.el10_0.aarch64 as a component of Red Hat Enterprise Linux CodeReady Linux Builder EUS (v. 10.0)
  • kernel-64k-debug-debuginfo-0:6.12.0-55.109.1.el10_0.aarch64 as a component of Red Hat Enterprise Linux Real Time EUS (v. 10.0)
  • kernel-64k-debug-devel-0:6.12.0-55.109.1.el10_0.aarch64 as a component of Red Hat Enterprise Linux AppStream EUS (v. 10.0)
  • kernel-64k-debug-devel-matched-0:6.12.0-55.109.1.el10_0.aarch64 as a component of Red Hat Enterprise Linux AppStream EUS (v. 10.0)
  • kernel-64k-debug-modules-0:6.12.0-55.109.1.el10_0.aarch64 as a component of Red Hat Enterprise Linux BaseOS EUS (v. 10.0)
  • kernel-64k-debug-modules-core-0:6.12.0-55.109.1.el10_0.aarch64 as a component of Red Hat Enterprise Linux BaseOS EUS (v. 10.0)
  • kernel-64k-debug-modules-extra-0:6.12.0-55.109.1.el10_0.aarch64 as a component of Red Hat Enterprise Linux BaseOS EUS (v. 10.0)
  • kernel-64k-debuginfo-0:6.12.0-55.109.1.el10_0.aarch64 as a component of Red Hat Enterprise Linux AppStream EUS (v. 10.0)
  • kernel-64k-debuginfo-0:6.12.0-55.109.1.el10_0.aarch64 as a component of Red Hat Enterprise Linux BaseOS EUS (v. 10.0)
  • kernel-64k-debuginfo-0:6.12.0-55.109.1.el10_0.aarch64 as a component of Red Hat Enterprise Linux CodeReady Linux Builder EUS (v. 10.0)
  • kernel-64k-debuginfo-0:6.12.0-55.109.1.el10_0.aarch64 as a component of Red Hat Enterprise Linux Real Time EUS (v. 10.0)
  • kernel-64k-devel-0:6.12.0-55.109.1.el10_0.aarch64 as a component of Red Hat Enterprise Linux AppStream EUS (v. 10.0)
  • kernel-64k-devel-matched-0:6.12.0-55.109.1.el10_0.aarch64 as a component of Red Hat Enterprise Linux AppStream EUS (v. 10.0)
  • kernel-64k-modules-0:6.12.0-55.109.1.el10_0.aarch64 as a component of Red Hat Enterprise Linux BaseOS EUS (v. 10.0)
  • +170 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. 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. Workaround: Mitigation for this issue is either not available or the currently available options don't meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability. Workaround: This flaw is triggered when the kernel SMB client processes crafted responses from a malicious or compromised SMB server. As a workaround, avoid mounting or accessing SMB/CIFS shares from untrusted servers, and disconnect existing mounts from servers that are not fully trusted. A complete fix requires updating to a kernel that contains the fix once it is available for the affected stream. Workaround: To mitigate this vulnerability, prevent the `cifs` kernel module from being loaded if SMB/CIFS network file systems are not required. 1. Add the module to the modprobe blacklist configuration: # echo "install cifs /bin/true" >> /etc/modprobe.d/disable-cifs.conf # echo "blacklist cifs" >> /etc/modprobe.d/disable-cifs.conf 2. If the module is currently loaded, unmount all active CIFS shares and unload the module: # modprobe -r cifs Caveats: Disabling the module prevents the system from mounting or accessing remote SMB/CIFS file shares. If the module cannot be unloaded immediately due to active usage, a system restart will be required for the configuration to take effect. 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 (13)