{ "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": "2026-10-21T20:43:33.349Z" }, "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", "versions": [ { "version": "0:3.1.10-1.el10_2.2", "lessThan": "*", "versionType": "rpm", "status": "unaffected" } ], "cpes": [ "cpe:/o:redhat:enterprise_linux:10.2" ] }, { "vendor": "Red Hat", "product": "Red Hat Enterprise Linux 10.0 Extended Update Support", "collectionURL": "https://access.redhat.com/downloads/content/package-browser/", "packageName": "corosync", "defaultStatus": "affected", "versions": [ { "version": "0:3.1.9-1.el10_0.3", "lessThan": "*", "versionType": "rpm", "status": "unaffected" } ], "cpes": [ "cpe:/o:redhat:enterprise_linux_eus:10.0" ] }, { "vendor": "Red Hat", 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"cpe:/a:redhat:rhel_eus_long_life:8.4::appstream", "cpe:/a:redhat:rhel_eus_long_life:8.4::highavailability", "cpe:/a:redhat:rhel_eus_long_life:8.4::resilientstorage" ] }, { "vendor": "Red Hat", "product": "Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support", "collectionURL": "https://access.redhat.com/downloads/content/package-browser/", "packageName": "corosync", "defaultStatus": "affected", "versions": [ { "version": "0:3.1.5-2.el8_6.2", "lessThan": "*", "versionType": "rpm", "status": "unaffected" } ], "cpes": [ "cpe:/a:redhat:rhel_aus:8.6::appstream", "cpe:/a:redhat:rhel_eus_long_life:8.6::appstream", "cpe:/a:redhat:rhel_eus_long_life:8.6::highavailability", "cpe:/a:redhat:rhel_eus_long_life:8.6::resilientstorage" ] }, { "vendor": "Red Hat", "product": "Red Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-On", "collectionURL": "https://access.redhat.com/downloads/content/package-browser/", "packageName": "corosync", "defaultStatus": "affected", 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"Red Hat Enterprise Linux 9.6 Extended Update Support", "collectionURL": "https://access.redhat.com/downloads/content/package-browser/", "packageName": "corosync", "defaultStatus": "affected", "versions": [ { "version": "0:3.1.9-2.el9_6.2", "lessThan": "*", "versionType": "rpm", "status": "unaffected" } ], "cpes": [ "cpe:/a:redhat:rhel_eus:9.6::appstream", "cpe:/a:redhat:rhel_eus:9.6::crb", "cpe:/a:redhat:rhel_eus:9.6::highavailability", "cpe:/a:redhat:rhel_eus:9.6::resilientstorage" ] }, { "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": "unaffected", "cpes": [ "cpe:/a:redhat:openshift:4" ] } ], "references": [ { "url": "https://access.redhat.com/errata/RHSA-2026:67872", "name": "RHSA-2026:67872", "tags": [ "vendor-advisory", "x_refsource_REDHAT" ] }, { "url": "https://access.redhat.com/errata/RHSA-2026:67873", "name": "RHSA-2026:67873", "tags": [ "vendor-advisory", "x_refsource_REDHAT" ] }, { "url": "https://access.redhat.com/errata/RHSA-2026:67878", "name": "RHSA-2026:67878", "tags": [ "vendor-advisory", "x_refsource_REDHAT" ] }, { "url": "https://access.redhat.com/errata/RHSA-2026:67879", "name": "RHSA-2026:67879", "tags": [ "vendor-advisory", "x_refsource_REDHAT" ] }, { "url": "https://access.redhat.com/errata/RHSA-2026:67880", "name": "RHSA-2026:67880", "tags": [ "vendor-advisory", "x_refsource_REDHAT" ] }, { "url": "https://access.redhat.com/errata/RHSA-2026:67881", "name": "RHSA-2026:67881", "tags": [ "vendor-advisory", "x_refsource_REDHAT" ] }, { "url": "https://access.redhat.com/errata/RHSA-2026:68574", "name": "RHSA-2026:68574", "tags": [ "vendor-advisory", "x_refsource_REDHAT" ] }, { "url": "https://access.redhat.com/errata/RHSA-2026:69277", "name": "RHSA-2026:69277", "tags": [ "vendor-advisory", "x_refsource_REDHAT" ] }, { "url": "https://access.redhat.com/errata/RHSA-2026:69278", "name": "RHSA-2026:69278", "tags": [ "vendor-advisory", "x_refsource_REDHAT" ] }, { "url": "https://access.redhat.com/errata/RHSA-2026:69279", "name": "RHSA-2026:69279", "tags": [ "vendor-advisory", "x_refsource_REDHAT" ] }, { "url": "https://access.redhat.com/errata/RHSA-2026:69280", "name": "RHSA-2026:69280", "tags": [ "vendor-advisory", "x_refsource_REDHAT" ] }, { "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": "2026-10-21T20:43:33.349Z" }, "x_generator": { "engine": "cvelib 1.8.0" } }, "adp": [ { "metrics": [ { "other": { "type": "ssvc", "content": { "timestamp": "2026-09-04T17:09:13.395902Z", "id": "CVE-2026-81665", "options": [ { "Exploitation": "none" }, { "Automatable": "no" }, { "Technical Impact": "total" } ], "role": "CISA Coordinator", "version": "2.0.3" } } } ], "title": "CISA ADP Vulnrichment", "providerMetadata": { "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-09-04T18:25:16.035Z" } } ] } }