{"affected":[{"defaultStatus":"affected","ecosystem":"https://access.redhat.com/downloads/content/package-browser/","packageName":"corosync","product":"Red Hat Enterprise Linux 10","source":"CNA: redhat","vendor":"Red Hat","versions":[]},{"defaultStatus":"affected","ecosystem":"https://access.redhat.com/downloads/content/package-browser/","packageName":"corosync","product":"Red Hat Enterprise Linux 7","source":"CNA: redhat","vendor":"Red Hat","versions":[]},{"defaultStatus":"affected","ecosystem":"https://access.redhat.com/downloads/content/package-browser/","packageName":"corosync","product":"Red Hat Enterprise Linux 8","source":"CNA: redhat","vendor":"Red Hat","versions":[]},{"defaultStatus":"affected","ecosystem":"https://access.redhat.com/downloads/content/package-browser/","packageName":"corosync","product":"Red Hat Enterprise Linux 9","source":"CNA: redhat","vendor":"Red Hat","versions":[]},{"defaultStatus":"affected","ecosystem":"https://access.redhat.com/downloads/content/package-browser/","packageName":"openshift/ose-rhel-coreos-9","product":"Red Hat OpenShift Container Platform 4","source":"CNA: redhat","vendor":"Red Hat","versions":[]},{"defaultStatus":"affected","ecosystem":"https://access.redhat.com/downloads/content/package-browser/","packageName":"rhcos","product":"Red Hat OpenShift Container Platform 4","source":"CNA: redhat","vendor":"Red Hat","versions":[]},{"defaultStatus":"affected","ecosystem":"https://access.redhat.com/downloads/content/package-browser/","packageName":"openshift/ose-rhel-coreos-9","product":"Red Hat OpenShift Container Platform 5","source":"CNA: redhat","vendor":"Red Hat","versions":[]}],"cveId":"CVE-2026-81666","cwes":["CWE-190"],"description":"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.","epss":{"date":"2026-11-03","percentile":0.15967,"score":0.00246},"exploits":[],"kev":null,"metrics":[{"score":6.5,"severity":"medium","source":"CNA: redhat","vector":"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","version":"3.1"}],"modifiedAt":1793728482305,"publishedAt":1788515166130,"references":[{"source":"CNA: redhat","tags":["vdb-entry","x_refsource_REDHAT"],"url":"https://access.redhat.com/security/cve/CVE-2026-81666"},{"source":"CNA: redhat","tags":["issue-tracking","x_refsource_REDHAT"],"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2524923"}],"remediation":[{"kind":"workaround","source":"CNA: redhat","text":"There is no complete mitigation for this vulnerability short of a fix, but the following steps reduce risk:\n\n1. Ensure cluster message authentication is enabled in corosync.conf (crypto_cipher=aes256, crypto_hash=sha256 with a shared key from corosync-keygen), which 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.\n2. Restrict network access to the cluster communication ports (default 5405-5412/UDP) to trusted cluster node addresses only.\n3. Where architecturally feasible, prefer 64-bit deployments, since the integer overflow described here does not occur on 64-bit systems."}],"revision":"9c064910b6ec33278208021c7b0f5e0677d8d4c2fa68e78bd539350b91bfa6ad","sources":[{"modifiedAt":1793728482305,"name":"CNA: redhat","retrievedAt":1793729450990,"url":"https://www.cve.org/CVERecord?id=CVE-2026-81666"},{"modifiedAt":null,"name":"FIRST EPSS","retrievedAt":1793729469231,"url":"https://api.first.org/data/v1/epss?cve=CVE-2026-81666"}],"ssvc":{"assessedAt":1788878490256,"automatable":"no","exploitation":"none","source":"ADP: CISA-ADP","technicalImpact":"partial"},"status":"published","title":"Corosync: corosync: integer overflow in check_memb_commit_token_sanity may bypass message length validation on 32-bit systems","updatedAt":1793729469231}