{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-81665", "assignerOrgId": "53f830b8-0a3f-465b-8143-3b8a9948e749", "state": "PUBLISHED", "assignerShortName": "redhat", "dateReserved": "2026-08-27T10:38:28.793Z", "datePublished": "2026-09-04T09:05:35.890Z", "dateUpdated": "2026-09-04T09:05:35.890Z"}, "containers": {"cna": {"title": "Corosync: corosync: heap-based buffer overflow in totempg assembly buffer during fragmented message reassembly", "metrics": [{"other": {"content": {"value": "Important", "namespace": "https://access.redhat.com/security/updates/classification/"}, "type": "Red Hat severity rating"}}, {"cvssV3_1": {"attackComplexity": "HIGH", "attackVector": "ADJACENT_NETWORK", "availabilityImpact": "HIGH", "baseScore": 7.5, "baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H", "version": "3.1"}, "format": "CVSS"}], "descriptions": [{"lang": "en", "value": "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."}], "affected": [{"vendor": "Red Hat", "product": "Red Hat Enterprise Linux 10", "collectionURL": "https://access.redhat.com/downloads/content/package-browser/", "packageName": "corosync", "defaultStatus": "affected", "cpes": ["cpe:/o:redhat:enterprise_linux:10"]}, {"vendor": "Red Hat", "product": "Red Hat Enterprise Linux 7", "collectionURL": "https://access.redhat.com/downloads/content/package-browser/", "packageName": "corosync", "defaultStatus": "affected", "cpes": ["cpe:/o:redhat:enterprise_linux:7"]}, {"vendor": "Red Hat", "product": "Red Hat Enterprise Linux 8", "collectionURL": "https://access.redhat.com/downloads/content/package-browser/", "packageName": "corosync", "defaultStatus": "affected", "cpes": ["cpe:/o:redhat:enterprise_linux:8"]}, {"vendor": "Red Hat", "product": "Red Hat Enterprise Linux 9", "collectionURL": "https://access.redhat.com/downloads/content/package-browser/", "packageName": "corosync", "defaultStatus": "affected", "cpes": ["cpe:/o:redhat:enterprise_linux:9"]}, {"vendor": "Red Hat", "product": "Red Hat OpenShift Container Platform 4", "collectionURL": "https://access.redhat.com/downloads/content/package-browser/", "packageName": "openshift/ose-rhel-coreos-9", "defaultStatus": "affected", "cpes": ["cpe:/a:redhat:openshift:4"]}, {"vendor": "Red Hat", "product": "Red Hat OpenShift Container Platform 4", "collectionURL": "https://access.redhat.com/downloads/content/package-browser/", "packageName": "rhcos", "defaultStatus": "affected", "cpes": ["cpe:/a:redhat:openshift:4"]}], "references": [{"url": "https://access.redhat.com/security/cve/CVE-2026-81665", "tags": ["vdb-entry", "x_refsource_REDHAT"]}, {"url": "https://bugzilla.redhat.com/show_bug.cgi?id=2524910", "name": "RHBZ#2524910", "tags": ["issue-tracking", "x_refsource_REDHAT"]}], "datePublic": "2026-09-04T08:30:05.029Z", "problemTypes": [{"descriptions": [{"cweId": "CWE-122", "description": "Heap-based Buffer Overflow", "lang": "en", "type": "CWE"}]}], "x_redhatCweChain": "CWE-122: Heap-based Buffer Overflow", "workarounds": [{"lang": "en", "value": "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."}], "timeline": [{"lang": "en", "time": "2026-08-23T00:00:00.000Z", "value": "Reported to Red Hat."}, {"lang": "en", "time": "2026-09-04T08:30:05.029Z", "value": "Made public."}], "credits": [{"lang": "en", "value": "Red Hat would like to thank Tristan Madani (Talence Security) for reporting this issue."}], "providerMetadata": {"orgId": "53f830b8-0a3f-465b-8143-3b8a9948e749", "shortName": "redhat", "dateUpdated": "2026-09-04T09:05:35.890Z"}, "x_generator": {"engine": "cvelib 1.8.0"}}}}

{}

{"affected": [{"affectedData": [{"collectionURL": "https://access.redhat.com/downloads/content/package-browser/", "cpes": ["cpe:/o:redhat:enterprise_linux:10"], "defaultStatus": "affected", "packageName": "corosync", "product": "Red Hat Enterprise Linux 10", "vendor": "Red Hat"}, {"collectionURL": "https://access.redhat.com/downloads/content/package-browser/", "cpes": ["cpe:/o:redhat:enterprise_linux:7"], "defaultStatus": "affected", "packageName": "corosync", "product": "Red Hat Enterprise Linux 7", "vendor": "Red Hat"}, {"collectionURL": "https://access.redhat.com/downloads/content/package-browser/", "cpes": ["cpe:/o:redhat:enterprise_linux:8"], "defaultStatus": "affected", "packageName": "corosync", "product": "Red Hat Enterprise Linux 8", "vendor": "Red Hat"}, {"collectionURL": "https://access.redhat.com/downloads/content/package-browser/", "cpes": ["cpe:/o:redhat:enterprise_linux:9"], "defaultStatus": "affected", "packageName": "corosync", "product": "Red Hat Enterprise Linux 9", "vendor": "Red Hat"}, {"collectionURL": "https://access.redhat.com/downloads/content/package-browser/", "cpes": ["cpe:/a:redhat:openshift:4"], "defaultStatus": "affected", "packageName": "openshift/ose-rhel-coreos-9", "product": "Red Hat OpenShift Container Platform 4", "vendor": "Red Hat"}, {"collectionURL": "https://access.redhat.com/downloads/content/package-browser/", "cpes": ["cpe:/a:redhat:openshift:4"], "defaultStatus": "affected", "packageName": "rhcos", "product": "Red Hat OpenShift Container Platform 4", "vendor": "Red Hat"}], "source": "secalert@redhat.com"}], "cveTags": [], "descriptions": [{"lang": "en", "value": "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."}], "id": "CVE-2026-81665", "lastModified": "2026-09-04T09:17:11.357", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "HIGH", "attackVector": "ADJACENT_NETWORK", "availabilityImpact": "HIGH", "baseScore": 7.5, "baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H", "version": "3.1"}, "exploitabilityScore": 1.6, "impactScore": 5.9, "source": "secalert@redhat.com", "type": "Primary"}]}, "published": "2026-09-04T09:17:11.357", "references": [{"source": "secalert@redhat.com", "url": "https://access.redhat.com/security/cve/CVE-2026-81665"}, {"source": "secalert@redhat.com", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2524910"}], "sourceIdentifier": "secalert@redhat.com", "vulnStatus": "Received", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-122"}], "source": "secalert@redhat.com", "type": "Primary"}]}

{}

{"created": "2026-09-04T10:30:17.943688+00:00", "updated": "2026-09-04T10:30:17.943694+00:00", "vendors": []}