{"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":[{"lessThan":"*","status":"unaffected","version":"0:3.1.10-1.el10_2.2","versionType":"rpm"}]},{"defaultStatus":"affected","ecosystem":"https://access.redhat.com/downloads/content/package-browser/","packageName":"corosync","product":"Red Hat Enterprise Linux 10.0 Extended Update Support","source":"CNA: redhat","vendor":"Red Hat","versions":[{"lessThan":"*","status":"unaffected","version":"0:3.1.9-1.el10_0.3","versionType":"rpm"}]},{"defaultStatus":"affected","ecosystem":"https://access.redhat.com/downloads/content/package-browser/","packageName":"corosync","product":"Red Hat Enterprise Linux 7 Extended Lifecycle Support","source":"CNA: redhat","vendor":"Red 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Enterprise Linux 9.2 Update Services for SAP Solutions","source":"CNA: redhat","vendor":"Red Hat","versions":[{"lessThan":"*","status":"unaffected","version":"0:3.1.7-1.el9_2.2","versionType":"rpm"}]},{"defaultStatus":"affected","ecosystem":"https://access.redhat.com/downloads/content/package-browser/","packageName":"corosync","product":"Red Hat Enterprise Linux 9.4 Update Services for SAP Solutions","source":"CNA: redhat","vendor":"Red Hat","versions":[{"lessThan":"*","status":"unaffected","version":"0:3.1.8-1.el9_4.2","versionType":"rpm"}]},{"defaultStatus":"affected","ecosystem":"https://access.redhat.com/downloads/content/package-browser/","packageName":"corosync","product":"Red Hat Enterprise Linux 9.6 Extended Update Support","source":"CNA: redhat","vendor":"Red Hat","versions":[{"lessThan":"*","status":"unaffected","version":"0:3.1.9-2.el9_6.2","versionType":"rpm"}]},{"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":"unaffected","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":[]},{"defaultStatus":"unaffected","ecosystem":"https://access.redhat.com/downloads/content/package-browser/","packageName":"rhcos","product":"Red Hat OpenShift Container Platform 5","source":"CNA: redhat","vendor":"Red Hat","versions":[]}],"cveId":"CVE-2026-81665","cwes":["CWE-122"],"description":"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.","epss":{"date":"2026-11-02","percentile":0.35885,"score":0.00416},"exploits":[],"kev":null,"metrics":[{"score":7.5,"severity":"high","source":"CNA: redhat","vector":"CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H","version":"3.1"},{"score":7.5,"severity":"high","source":"NVD: secalert@redhat.com","vector":"CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H","version":"3.1"}],"modifiedAt":1793636264457,"publishedAt":1788512735890,"references":[{"source":"CNA: redhat","tags":["vendor-advisory","x_refsource_REDHAT"],"url":"https://access.redhat.com/errata/RHSA-2026:67872"},{"source":"CNA: redhat","tags":["vendor-advisory","x_refsource_REDHAT"],"url":"https://access.redhat.com/errata/RHSA-2026:67873"},{"source":"CNA: redhat","tags":["vendor-advisory","x_refsource_REDHAT"],"url":"https://access.redhat.com/errata/RHSA-2026:67878"},{"source":"CNA: redhat","tags":["vendor-advisory","x_refsource_REDHAT"],"url":"https://access.redhat.com/errata/RHSA-2026:67879"},{"source":"CNA: redhat","tags":["vendor-advisory","x_refsource_REDHAT"],"url":"https://access.redhat.com/errata/RHSA-2026:67880"},{"source":"CNA: redhat","tags":["vendor-advisory","x_refsource_REDHAT"],"url":"https://access.redhat.com/errata/RHSA-2026:67881"},{"source":"CNA: redhat","tags":["vendor-advisory","x_refsource_REDHAT"],"url":"https://access.redhat.com/errata/RHSA-2026:68574"},{"source":"CNA: redhat","tags":["vendor-advisory","x_refsource_REDHAT"],"url":"https://access.redhat.com/errata/RHSA-2026:69277"},{"source":"CNA: redhat","tags":["vendor-advisory","x_refsource_REDHAT"],"url":"https://access.redhat.com/errata/RHSA-2026:69278"},{"source":"CNA: redhat","tags":["vendor-advisory","x_refsource_REDHAT"],"url":"https://access.redhat.com/errata/RHSA-2026:69279"},{"source":"CNA: redhat","tags":["vendor-advisory","x_refsource_REDHAT"],"url":"https://access.redhat.com/errata/RHSA-2026:69280"},{"source":"CNA: redhat","tags":["vdb-entry","x_refsource_REDHAT"],"url":"https://access.redhat.com/security/cve/CVE-2026-81665"},{"source":"CNA: redhat","tags":["issue-tracking","x_refsource_REDHAT"],"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2524910"},{"source":"secalert@redhat.com","tags":[],"url":"https://access.redhat.com/errata/RHSA-2026:67872"},{"source":"secalert@redhat.com","tags":[],"url":"https://access.redhat.com/errata/RHSA-2026:67873"},{"source":"secalert@redhat.com","tags":[],"url":"https://access.redhat.com/errata/RHSA-2026:67878"},{"source":"secalert@redhat.com","tags":[],"url":"https://access.redhat.com/errata/RHSA-2026:67879"},{"source":"secalert@redhat.com","tags":[],"url":"https://access.redhat.com/errata/RHSA-2026:67880"},{"source":"secalert@redhat.com","tags":[],"url":"https://access.redhat.com/errata/RHSA-2026:67881"},{"source":"secalert@redhat.com","tags":[],"url":"https://access.redhat.com/errata/RHSA-2026:68574"},{"source":"secalert@redhat.com","tags":[],"url":"https://access.redhat.com/errata/RHSA-2026:69277"},{"source":"secalert@redhat.com","tags":[],"url":"https://access.redhat.com/errata/RHSA-2026:69278"},{"source":"secalert@redhat.com","tags":[],"url":"https://access.redhat.com/errata/RHSA-2026:69279"},{"source":"secalert@redhat.com","tags":[],"url":"https://access.redhat.com/errata/RHSA-2026:69280"},{"source":"secalert@redhat.com","tags":[],"url":"https://access.redhat.com/security/cve/CVE-2026-81665"},{"source":"secalert@redhat.com","tags":[],"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2524910"}],"remediation":[{"kind":"workaround","source":"CNA: redhat","text":"There is no complete mitigation for this vulnerability short of a fix, but the following steps significantly reduce risk:\n\n1. 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.\n2. Restrict network access to the cluster communication ports (default 5405-5412/UDP) to trusted cluster node addresses only, using firewalld or other firewall rules.\n3. Ensure SELinux is running in enforcing mode on cluster nodes to limit the impact of any successful exploitation."}],"revision":"2e27f3400b88284040350ac3786745c5fc179e34d007fa821ad353d2eb6920ab","sources":[{"modifiedAt":1793634369678,"name":"CNA: redhat","retrievedAt":1793635786983,"url":"https://www.cve.org/CVERecord?id=CVE-2026-81665"},{"modifiedAt":1793636264457,"name":"NVD","retrievedAt":1793643376816,"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-81665"},{"modifiedAt":null,"name":"FIRST EPSS","retrievedAt":1793635805888,"url":"https://api.first.org/data/v1/epss?cve=CVE-2026-81665"}],"ssvc":{"assessedAt":1788541753395,"automatable":"no","exploitation":"none","source":"ADP: CISA-ADP","technicalImpact":"total"},"status":"published","title":"Corosync: corosync: heap-based buffer overflow in totempg assembly buffer during fragmented message reassembly","updatedAt":1793643376816}