Amazon Linux 2 (EOS) Security Advisory: ALAS2-2026-3955
Advisory Released Date: 2026-09-28
Advisory Updated Date: 2026-09-28
A heap-based buffer overflow was found in Corosync's Totem Process Group (totempg) message reassembly. When processing fragmented multicast messages, the buffer used to reassemble fragments lacks a runtime bounds check in release builds. A network-adjacent attacker able to send crafted multicast protocol messages to the cluster could cause a heap buffer overflow with attacker-controlled data. This can crash the Corosync daemon, causing a denial of service to the entire cluster, and may potentially allow further exploitation given sufficient heap-corruption control. (CVE-2026-81665)
Affected Packages:
corosync
Note:
This advisory is applicable to Amazon Linux 2 (AL2) Core repository. Visit this FAQ section for the difference between AL2 Core and AL2 Extras advisories.
Issue Correction:
Run yum update corosync or yum update --advisory ALAS2-2026-3955 to update your system.
aarch64:
corosync-2.4.3-6.amzn2.1.2.aarch64
corosync-debuginfo-2.4.3-6.amzn2.1.2.aarch64
corosynclib-2.4.3-6.amzn2.1.2.aarch64
corosynclib-devel-2.4.3-6.amzn2.1.2.aarch64
corosync-qdevice-2.4.3-6.amzn2.1.2.aarch64
corosync-qnetd-2.4.3-6.amzn2.1.2.aarch64
spausedd-2.4.3-6.amzn2.1.2.aarch64
i686:
corosync-2.4.3-6.amzn2.1.2.i686
corosync-debuginfo-2.4.3-6.amzn2.1.2.i686
corosynclib-2.4.3-6.amzn2.1.2.i686
corosynclib-devel-2.4.3-6.amzn2.1.2.i686
corosync-qdevice-2.4.3-6.amzn2.1.2.i686
corosync-qnetd-2.4.3-6.amzn2.1.2.i686
spausedd-2.4.3-6.amzn2.1.2.i686
src:
corosync-2.4.3-6.amzn2.1.2.src
x86_64:
corosync-2.4.3-6.amzn2.1.2.x86_64
corosync-debuginfo-2.4.3-6.amzn2.1.2.x86_64
corosynclib-2.4.3-6.amzn2.1.2.x86_64
corosynclib-devel-2.4.3-6.amzn2.1.2.x86_64
corosync-qdevice-2.4.3-6.amzn2.1.2.x86_64
corosync-qnetd-2.4.3-6.amzn2.1.2.x86_64
spausedd-2.4.3-6.amzn2.1.2.x86_64