RHSA-2026:68574HighCVSS 7.5

Red Hat Security Advisory: corosync security update

Published
September 17, 2026
Last Modified
September 21, 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 products38

  • Red Hat Enterprise Linux Server HighAvailability (v. 7 ELS)
  • Red Hat Enterprise Linux Server ResilientStorage (v. 7 ELS)
  • corosync-0:2.4.5-7.el7_9.4.ppc64le as a component of Red Hat Enterprise Linux Server HighAvailability (v. 7 ELS)
  • corosync-0:2.4.5-7.el7_9.4.ppc64le as a component of Red Hat Enterprise Linux Server ResilientStorage (v. 7 ELS)
  • corosync-0:2.4.5-7.el7_9.4.src as a component of Red Hat Enterprise Linux Server HighAvailability (v. 7 ELS)
  • corosync-0:2.4.5-7.el7_9.4.src as a component of Red Hat Enterprise Linux Server ResilientStorage (v. 7 ELS)
  • corosync-0:2.4.5-7.el7_9.4.x86_64 as a component of Red Hat Enterprise Linux Server HighAvailability (v. 7 ELS)
  • corosync-0:2.4.5-7.el7_9.4.x86_64 as a component of Red Hat Enterprise Linux Server ResilientStorage (v. 7 ELS)
  • corosync-debuginfo-0:2.4.5-7.el7_9.4.i686 as a component of Red Hat Enterprise Linux Server HighAvailability (v. 7 ELS)
  • corosync-debuginfo-0:2.4.5-7.el7_9.4.i686 as a component of Red Hat Enterprise Linux Server ResilientStorage (v. 7 ELS)
  • corosync-debuginfo-0:2.4.5-7.el7_9.4.ppc64le as a component of Red Hat Enterprise Linux Server HighAvailability (v. 7 ELS)
  • corosync-debuginfo-0:2.4.5-7.el7_9.4.ppc64le as a component of Red Hat Enterprise Linux Server ResilientStorage (v. 7 ELS)
  • corosync-debuginfo-0:2.4.5-7.el7_9.4.x86_64 as a component of Red Hat Enterprise Linux Server HighAvailability (v. 7 ELS)
  • corosync-debuginfo-0:2.4.5-7.el7_9.4.x86_64 as a component of Red Hat Enterprise Linux Server ResilientStorage (v. 7 ELS)
  • corosync-qdevice-0:2.4.5-7.el7_9.4.ppc64le as a component of Red Hat Enterprise Linux Server HighAvailability (v. 7 ELS)
  • corosync-qdevice-0:2.4.5-7.el7_9.4.ppc64le as a component of Red Hat Enterprise Linux Server ResilientStorage (v. 7 ELS)
  • corosync-qdevice-0:2.4.5-7.el7_9.4.x86_64 as a component of Red Hat Enterprise Linux Server HighAvailability (v. 7 ELS)
  • corosync-qdevice-0:2.4.5-7.el7_9.4.x86_64 as a component of Red Hat Enterprise Linux Server ResilientStorage (v. 7 ELS)
  • corosync-qnetd-0:2.4.5-7.el7_9.4.ppc64le as a component of Red Hat Enterprise Linux Server HighAvailability (v. 7 ELS)
  • corosync-qnetd-0:2.4.5-7.el7_9.4.ppc64le as a component of Red Hat Enterprise Linux Server ResilientStorage (v. 7 ELS)
  • corosync-qnetd-0:2.4.5-7.el7_9.4.x86_64 as a component of Red Hat Enterprise Linux Server HighAvailability (v. 7 ELS)
  • corosync-qnetd-0:2.4.5-7.el7_9.4.x86_64 as a component of Red Hat Enterprise Linux Server ResilientStorage (v. 7 ELS)
  • corosynclib-0:2.4.5-7.el7_9.4.i686 as a component of Red Hat Enterprise Linux Server HighAvailability (v. 7 ELS)
  • corosynclib-0:2.4.5-7.el7_9.4.i686 as a component of Red Hat Enterprise Linux Server ResilientStorage (v. 7 ELS)
  • corosynclib-0:2.4.5-7.el7_9.4.ppc64le as a component of Red Hat Enterprise Linux Server HighAvailability (v. 7 ELS)
  • corosynclib-0:2.4.5-7.el7_9.4.ppc64le as a component of Red Hat Enterprise Linux Server ResilientStorage (v. 7 ELS)
  • corosynclib-0:2.4.5-7.el7_9.4.x86_64 as a component of Red Hat Enterprise Linux Server HighAvailability (v. 7 ELS)
  • corosynclib-0:2.4.5-7.el7_9.4.x86_64 as a component of Red Hat Enterprise Linux Server ResilientStorage (v. 7 ELS)
  • corosynclib-devel-0:2.4.5-7.el7_9.4.i686 as a component of Red Hat Enterprise Linux Server HighAvailability (v. 7 ELS)
  • corosynclib-devel-0:2.4.5-7.el7_9.4.i686 as a component of Red Hat Enterprise Linux Server ResilientStorage (v. 7 ELS)
  • +8 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)