Security advisory

{
  "id": "78881b4b72e4e147585991f36b41944d0e14f99f29ad63c896695abd49e85a1d",
  "url": "https://osv.dev/vulnerability/CVE-2026-5947",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "CVE-2026-5947",
    "summary": "Undefined behavior may result due to a race condition leading to a use-after-free violation. If BIND receives an incoming DNS message signed with SIG(0), it begins work to validate that signature. If, during that validation, the \"recursive-clients\" limit is reached (as would occur during a query flood), and that same DNS message is discarded per the limit, there is a brief window of time while the SIG(0) validation may attempt to read the now-discarded DNS message. This issue affects BIND 9 versions 9.20.0 through 9.20.22, 9.21.0 through 9.21.21, and 9.20.9-S1 through 9.20.22-S1. BIND 9 versions 9.18.28 through 9.18.49 and 9.18.28-S1 through 9.18.49-S1 are NOT affected.",
    "evidence": "osv:CVE-2026-5947",
    "products": [],
    "severity": "medium",
    "structured": {
      "id": "CVE-2026-5947",
      "aliases": [
        "CVE-2026-5947"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/isc-projects/bind9",
              "type": "GIT",
              "events": [
                {
                  "introduced": "14bbdfc7b9db0870a0b8941ca8812d9983fdba1a"
                },
                {
                  "fixed": "7d0b4d4d436e7b950225a533e5bc56d8f935cc1c"
                },
                {
                  "introduced": "b732da695eecc0526950e2c722cde0bf23e5a070"
                },
                {
                  "fixed": "02a7b2c8a549b79cf885d1a0cda28b74de22d197"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "cpe": "cpe:2.3:a:isc:bind:*:*:*:*:-:*:*:*",
                    "range": [
                      {
                        "introduced": "9.20.0"
                      },
                      {
                        "fixed": "9.20.23"
                      }
                    ],
                    "source": "CPE_RANGE"
                  },
                  {
                    "cpe": "cpe:2.3:a:isc:bind:*:*:*:*:-:*:*:*",
                    "range": [
                      {
                        "introduced": "9.21.0"
                      },
                      {
                        "fixed": "9.21.22"
                      }
                    ],
                    "source": "CPE_RANGE"
                  }
                ]
              }
            }
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-5947.json"
          }
        },
        {
          "ranges": [
            {
              "repo": "https://gitlab.isc.org/isc-projects/bind9",
              "type": "GIT",
              "events": [
                {
                  "introduced": "14bbdfc7b9db0870a0b8941ca8812d9983fdba1a"
                },
                {
                  "fixed": "7d0b4d4d436e7b950225a533e5bc56d8f935cc1c"
                },
                {
                  "introduced": "b732da695eecc0526950e2c722cde0bf23e5a070"
                },
                {
                  "fixed": "02a7b2c8a549b79cf885d1a0cda28b74de22d197"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "cpe": "cpe:2.3:a:isc:bind:*:*:*:*:-:*:*:*",
                    "range": [
                      {
                        "introduced": "9.20.0"
                      },
                      {
                        "fixed": "9.20.23"
                      }
                    ],
                    "source": "CPE_RANGE"
                  },
                  {
                    "cpe": "cpe:2.3:a:isc:bind:*:*:*:*:-:*:*:*",
                    "range": [
                      {
                        "introduced": "9.21.0"
                      },
                      {
                        "fixed": "9.21.22"
                      }
                    ],
                    "source": "CPE_RANGE"
                  }
                ]
              }
            }
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-5947.json"
          }
        }
      ],
      "modified": "2026-10-24T10:30:23.734607051Z",
      "provider": "osv",
      "references": [
        "https://access.redhat.com/security/cve/CVE-2026-5947",
        "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-5947.json",
        "https://access.redhat.com/errata/RHSA-2026:7412",
        "https://kb.isc.org/docs/cve-2026-5947",
        "https://bugzilla.redhat.com/show_bug.cgi?id=2479772",
        "https://downloads.isc.org/isc/bind9/9.20.23",
        "https://downloads.isc.org/isc/bind9/9.21.22"
      ],
      "provider_metadata": {}
    },
    "related_cves": [
      {
        "value": "CVE-2026-5947",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 430992,
  "published_at": "2026-05-20T13:16:40.303+00:00"
}