Detections
Analytics

Amazon Linux 2 : corosync (ALAS-2026-3955)

high Nessus Plugin ID 351024

Synopsis

The remote Amazon Linux 2 host is missing a security update.

Description

The version of corosync installed on the remote host is prior to 2.4.3-6. It is, therefore, affected by a vulnerability as referenced in the ALAS2-2026-3955 advisory.

 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)

Tenable has extracted the preceding description block directly from the tested product security advisory.

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

Solution

Run 'yum update corosync' or or 'yum update --advisory ALAS2-2026-3955' to update your system.

See Also

https://alas.aws.amazon.com//AL2/ALAS2-2026-3955.html

https://alas.aws.amazon.com/faqs.html

https://explore.alas.aws.amazon.com/CVE-2026-81665.html

Plugin Details

Severity: High

ID: 351024

File Name: al2_ALAS-2026-3955.nasl

Version: 1.1

Type: Local

Agent: unix

Published: 9/29/2026

Updated: 9/29/2026

Supported Sensors: Frictionless Assessment AWS, Frictionless Assessment Agent, Nessus Agent, Agentless Assessment, Continuous Assessment, Tenable Cloud Security, Tenable Self-Hosted Container Security, Nessus

Risk Information

VPR

Risk Factor: Medium

Score: 4.9

Percentile: 58.21

CVSS v2

Risk Factor: Medium

Base Score: 6.8

Temporal Score: 5

Vector: CVSS2#AV:A/AC:H/Au:N/C:C/I:C/A:C

CVSS Score Source: CVE-2026-81665

CVSS v3

Risk Factor: High

Base Score: 7.5

Temporal Score: 6.5

Vector: CVSS:3.0/AV:A/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

Temporal Vector: CVSS:3.0/E:U/RL:O/RC:C

Vulnerability Information

CPE: cpe:/o:amazon:linux:2, p-cpe:/a:amazon:linux:corosync-debuginfo, p-cpe:/a:amazon:linux:corosync-qdevice, p-cpe:/a:amazon:linux:corosync-qnetd, p-cpe:/a:amazon:linux:corosync, p-cpe:/a:amazon:linux:corosynclib-devel, p-cpe:/a:amazon:linux:corosynclib, p-cpe:/a:amazon:linux:spausedd

Required KB Items: Host/local_checks_enabled, Host/AmazonLinux/release, Host/AmazonLinux/rpm-list

Exploit Ease: No known exploits are available

Patch Publication Date: 9/28/2026

Vulnerability Publication Date: 9/4/2026

Reference Information

CVE: CVE-2026-81665