CVE-2026-81665

Full vulnerability record from the local CVENow database.
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.
Severity
HIGH
CVSS score
7.5 (v3.1)
Vulnerability status
Awaiting Analysis
Source identifier
[email protected]
Published
2026-09-04 09:17:11.357000
Last modified
2026-10-21 21:19:16.673000
View original CVE JSON
{
  "id": "CVE-2026-81665",
  "sourceIdentifier": "[email protected]",
  "published": "2026-09-04T09:17:11.357",
  "lastModified": "2026-10-21T21:19:16.673",
  "vulnStatus": "Awaiting Analysis",
  "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."
    }
  ],
  "affected": [
    {
      "source": "[email protected]",
      "affectedData": [
        {
          "vendor": "Red Hat",
          "product": "Red Hat Enterprise Linux 10",
          "defaultStatus": "affected",
          "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
          "packageName": "corosync",
          "cpes": [
            "cpe:/o:redhat:enterprise_linux:10.2"
          ],
          "versions": [
            {
              "version": "0:3.1.10-1.el10_2.2",
              "lessThan": "*",
              "versionType": "rpm",
              "status": "unaffected"
            }
          ]
        },
        {
          "vendor": "Red Hat",
          "product": "Red Hat Enterprise Linux 10.0 Extended Update Support",
          "defaultStatus": "affected",
          "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
          "packageName": "corosync",
          "cpes": [
            "cpe:/o:redhat:enterprise_linux_eus:10.0"
          ],
          "versions": [
            {
              "version": "0:3.1.9-1.el10_0.3",
              "lessThan": "*",
              "versionType": "rpm",
              "status": "unaffected"
            }
          ]
        },
        {
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          "product": "Red Hat Enterprise Linux 7 Extended Lifecycle Support",
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          "packageName": "corosync",
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            }
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            "cpe:/a:redhat:rhel_eus_long_life:8.4::highavailability",
            "cpe:/a:redhat:rhel_eus_long_life:8.4::resilientstorage"
          ],
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              "lessThan": "*",
              "versionType": "rpm",
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            "cpe:/a:redhat:rhel_eus_long_life:8.6::appstream",
            "cpe:/a:redhat:rhel_eus_long_life:8.6::highavailability",
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              "lessThan": "*",
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              "status": "unaffected"
            }
          ]
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        {
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            "cpe:/a:redhat:rhel_eus_long_life:8.6::highavailability",
            "cpe:/a:redhat:rhel_eus_long_life:8.6::resilientstorage"
          ],
          "versions": [
            {
              "version": "0:3.1.5-2.el8_6.2",
              "lessThan": "*",
              "versionType": "rpm",
              "status": "unaffected"
            }
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        },
        {
          "vendor": "Red Hat",
          "product": "Red Hat Enterprise Linux 8.8 Telecommunications Update Service",
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        {
          "vendor": "Red Hat",
          "product": "Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions",
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          ],
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        {
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            }
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        {
          "vendor": "Red Hat",
          "product": "Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions",
          "defaultStatus": "affected",
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            "cpe:/a:redhat:rhel_e4s:9.2::resilientstorage"
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            {
              "version": "0:3.1.7-1.el9_2.2",
              "lessThan": "*",
              "versionType": "rpm",
              "status": "unaffected"
            }
          ]
        },
        {
          "vendor": "Red Hat",
          "product": "Red Hat Enterprise Linux 9.4 Update Services for SAP Solutions",
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              "status": "unaffected"
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        {
          "vendor": "Red Hat",
          "product": "Red Hat OpenShift Container Platform 4",
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          "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
          "packageName": "openshift/ose-rhel-coreos-9",
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          "product": "Red Hat OpenShift Container Platform 4",
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          "packageName": "rhcos",
          "cpes": [
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  ],
  "metrics": {
    "cvssMetricV31": [
      {
        "source": "[email protected]",
        "type": "Secondary",
        "cvssData": {
          "version": "3.1",
          "vectorString": "CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H",
          "baseScore": 7.5,
          "baseSeverity": "HIGH",
          "attackVector": "ADJACENT_NETWORK",
          "attackComplexity": "HIGH",
          "privilegesRequired": "NONE",
          "userInteraction": "NONE",
          "scope": "UNCHANGED",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "availabilityImpact": "HIGH"
        },
        "exploitabilityScore": 1.6,
        "impactScore": 5.9
      }
    ],
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        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
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          "id": "CVE-2026-81665",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "total"
            }
          ],
          "role": "CISA Coordinator",
          "version": "2.0.3"
        }
      }
    ]
  },
  "weaknesses": [
    {
      "source": "[email protected]",
      "type": "Secondary",
      "description": [
        {
          "lang": "en",
          "value": "CWE-122"
        }
      ]
    }
  ],
  "references": [
    {
      "url": "https://access.redhat.com/errata/RHSA-2026:67872",
      "source": "[email protected]"
    },
    {
      "url": "https://access.redhat.com/errata/RHSA-2026:67873",
      "source": "[email protected]"
    },
    {
      "url": "https://access.redhat.com/errata/RHSA-2026:67878",
      "source": "[email protected]"
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    {
      "url": "https://access.redhat.com/errata/RHSA-2026:67879",
      "source": "[email protected]"
    },
    {
      "url": "https://access.redhat.com/errata/RHSA-2026:67880",
      "source": "[email protected]"
    },
    {
      "url": "https://access.redhat.com/errata/RHSA-2026:67881",
      "source": "[email protected]"
    },
    {
      "url": "https://access.redhat.com/errata/RHSA-2026:68574",
      "source": "[email protected]"
    },
    {
      "url": "https://access.redhat.com/errata/RHSA-2026:69277",
      "source": "[email protected]"
    },
    {
      "url": "https://access.redhat.com/errata/RHSA-2026:69278",
      "source": "[email protected]"
    },
    {
      "url": "https://access.redhat.com/errata/RHSA-2026:69279",
      "source": "[email protected]"
    },
    {
      "url": "https://access.redhat.com/errata/RHSA-2026:69280",
      "source": "[email protected]"
    },
    {
      "url": "https://access.redhat.com/security/cve/CVE-2026-81665",
      "source": "[email protected]"
    },
    {
      "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2524910",
      "source": "[email protected]"
    }
  ]
}