{"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","product":"Red Hat Enterprise Linux 7 Extended Lifecycle 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9","collectionURL":"https://access.redhat.com/downloads/content/package-browser/","packageName":"corosync","defaultStatus":"affected","versions":[{"version":"0:3.1.10-1.el9_8.2","lessThan":"*","versionType":"rpm","status":"unaffected"}],"cpes":["cpe:/a:redhat:enterprise_linux:9::appstream","cpe:/a:redhat:enterprise_linux:9::crb","cpe:/a:redhat:enterprise_linux:9::highavailability","cpe:/a:redhat:enterprise_linux:9::resilientstorage"]},{"vendor":"Red Hat","product":"Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions","collectionURL":"https://access.redhat.com/downloads/content/package-browser/","packageName":"corosync","defaultStatus":"affected","versions":[{"version":"0:3.1.7-1.el9_2.2","lessThan":"*","versionType":"rpm","status":"unaffected"}],"cpes":["cpe:/a:redhat:rhel_e4s:9.2::appstream","cpe:/a:redhat:rhel_e4s:9.2::highavailability","cpe:/a:redhat:rhel_e4s:9.2::resilientstorage"]},{"vendor":"Red Hat","product":"Red Hat Enterprise Linux 9.4 Update Services for SAP 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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"}}]}}