RHSA-2026:67878HighCVSS 7.5

Red Hat Security Advisory: corosync security update

Published
September 16, 2026
Last Modified
September 16, 2026

🔗 CVE IDs covered (1)

CVE-2026-81665 →

📋 Description

CVE-2026-81665 — corosync: corosync: heap-based buffer overflow in totempg assembly buffer during fragmented message reassembly

🎯 Affected products71

  • Red Hat Enterprise Linux AppStream E4S (v.9.4)
  • Red Hat Enterprise Linux High Availability E4S (v.9.4)
  • Red Hat Enterprise Linux Resilient Storage E4S (v.9.4)
  • corosync-0:3.1.8-1.el9_4.2.aarch64 as a component of Red Hat Enterprise Linux High Availability E4S (v.9.4)
  • corosync-0:3.1.8-1.el9_4.2.ppc64le as a component of Red Hat Enterprise Linux High Availability E4S (v.9.4)
  • corosync-0:3.1.8-1.el9_4.2.ppc64le as a component of Red Hat Enterprise Linux Resilient Storage E4S (v.9.4)
  • corosync-0:3.1.8-1.el9_4.2.s390x as a component of Red Hat Enterprise Linux High Availability E4S (v.9.4)
  • corosync-0:3.1.8-1.el9_4.2.s390x as a component of Red Hat Enterprise Linux Resilient Storage E4S (v.9.4)
  • corosync-0:3.1.8-1.el9_4.2.src as a component of Red Hat Enterprise Linux AppStream E4S (v.9.4)
  • corosync-0:3.1.8-1.el9_4.2.x86_64 as a component of Red Hat Enterprise Linux High Availability E4S (v.9.4)
  • corosync-0:3.1.8-1.el9_4.2.x86_64 as a component of Red Hat Enterprise Linux Resilient Storage E4S (v.9.4)
  • corosync-debuginfo-0:3.1.8-1.el9_4.2.aarch64 as a component of Red Hat Enterprise Linux High Availability E4S (v.9.4)
  • corosync-debuginfo-0:3.1.8-1.el9_4.2.i686 as a component of Red Hat Enterprise Linux AppStream E4S (v.9.4)
  • corosync-debuginfo-0:3.1.8-1.el9_4.2.i686 as a component of Red Hat Enterprise Linux High Availability E4S (v.9.4)
  • corosync-debuginfo-0:3.1.8-1.el9_4.2.i686 as a component of Red Hat Enterprise Linux Resilient Storage E4S (v.9.4)
  • corosync-debuginfo-0:3.1.8-1.el9_4.2.ppc64le as a component of Red Hat Enterprise Linux High Availability E4S (v.9.4)
  • corosync-debuginfo-0:3.1.8-1.el9_4.2.ppc64le as a component of Red Hat Enterprise Linux Resilient Storage E4S (v.9.4)
  • corosync-debuginfo-0:3.1.8-1.el9_4.2.s390x as a component of Red Hat Enterprise Linux High Availability E4S (v.9.4)
  • corosync-debuginfo-0:3.1.8-1.el9_4.2.s390x as a component of Red Hat Enterprise Linux Resilient Storage E4S (v.9.4)
  • corosync-debuginfo-0:3.1.8-1.el9_4.2.x86_64 as a component of Red Hat Enterprise Linux AppStream E4S (v.9.4)
  • corosync-debuginfo-0:3.1.8-1.el9_4.2.x86_64 as a component of Red Hat Enterprise Linux High Availability E4S (v.9.4)
  • corosync-debuginfo-0:3.1.8-1.el9_4.2.x86_64 as a component of Red Hat Enterprise Linux Resilient Storage E4S (v.9.4)
  • corosync-debugsource-0:3.1.8-1.el9_4.2.aarch64 as a component of Red Hat Enterprise Linux High Availability E4S (v.9.4)
  • corosync-debugsource-0:3.1.8-1.el9_4.2.i686 as a component of Red Hat Enterprise Linux AppStream E4S (v.9.4)
  • corosync-debugsource-0:3.1.8-1.el9_4.2.i686 as a component of Red Hat Enterprise Linux High Availability E4S (v.9.4)
  • corosync-debugsource-0:3.1.8-1.el9_4.2.i686 as a component of Red Hat Enterprise Linux Resilient Storage E4S (v.9.4)
  • corosync-debugsource-0:3.1.8-1.el9_4.2.ppc64le as a component of Red Hat Enterprise Linux High Availability E4S (v.9.4)
  • corosync-debugsource-0:3.1.8-1.el9_4.2.ppc64le as a component of Red Hat Enterprise Linux Resilient Storage E4S (v.9.4)
  • corosync-debugsource-0:3.1.8-1.el9_4.2.s390x as a component of Red Hat Enterprise Linux High Availability E4S (v.9.4)
  • corosync-debugsource-0:3.1.8-1.el9_4.2.s390x as a component of Red Hat Enterprise Linux Resilient Storage E4S (v.9.4)
  • +41 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 Workaround: There is no complete mitigation for this vulnerability short of a fix, but the following steps significantly reduce risk: 1. Ensure cluster message authentication is enabled in corosync.conf: set crypto_cipher to aes256 and crypto_hash to sha256 (or stronger) in the totem {} block, with a shared key generated by corosync-keygen. This is the default when clusters are configured via 'pcs cluster setup', and disabling it (cipher=none/hash=none) is an explicitly unsupported configuration per upstream maintainer guidance. 2. Restrict network access to the cluster communication ports (default 5405-5412/UDP) to trusted cluster node addresses only, using firewalld or other firewall rules. 3. Ensure SELinux is running in enforcing mode on cluster nodes to limit the impact of any successful exploitation.

🔗 References (4)