---
id: CVE-2026-81666
title: >-
  An integer overflow was found in Corosync's handling of membership commit
  token messages
summary: >-
  An integer overflow was found in Corosync's handling of membership commit
  token messages. The length-validation check for these messages can be bypassed
  on 32-bit systems due to an integer overflow in the calculation of the
  expected mess…
severity: medium
cvss: 6.5
cvssVector: 'CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'
cwe:
  - CWE-190
vendor: Red Hat
product: corosync
affected:
  - corosync (all versions)
  - corosync (all versions)
  - corosync (all versions)
  - corosync (all versions)
  - rhcos (all versions)
published: '2026-09-04'
updated: '2026-09-08'
sourceUpdated: '2026-09-08T19:08:15.590'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-81666'
references:
  - url: 'https://access.redhat.com/security/cve/CVE-2026-81666'
    label: secalert@redhat.com
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2524923'
    label: secalert@redhat.com
tags:
  - nvd
  - cve.org
epss: 0.00311
epssPercentile: 0.21427
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-09-08T14:41:30.256254Z'
ingestedAt: '2026-09-08T15:33:26.960Z'
---

## Overview

An integer overflow was found in Corosync's handling of membership commit token messages. The length-validation check for these messages can be bypassed on 32-bit systems due to an integer overflow in the calculation of the expected message length, allowing a crafted network packet to trigger an out-of-bounds memory access that crashes the Corosync daemon. This results in a denial of service for the affected cluster node. The overflow does not occur on 64-bit systems, where the length calculation is correctly performed in 64-bit arithmetic.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.