Security advisory

{
  "id": "93748aa4220544f6722393eec51ab1fe712262f35abeecaa12e207ab0c1e2fee",
  "url": "https://osv.dev/vulnerability/CVE-2026-4891",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "CVE-2026-4891",
    "summary": "A heap-based out-of-bounds read vulnerability in the DNSSEC validation of dnsmasq allows remote attackers to cause a denial of service via a crafted DNS packet.",
    "evidence": "osv:CVE-2026-4891",
    "products": [],
    "severity": "medium",
    "structured": {
      "id": "CVE-2026-4891",
      "aliases": [
        "CVE-2026-4891"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/pi-hole/ftl",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "82c58cc45435ddd77875daf368cf64398bc15966"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "fixed": "82c58cc45435ddd77875daf368cf64398bc15966"
                      }
                    ],
                    "source": "REFERENCES_TAG",
                    "original_tag": "v6.6.2"
                  }
                ]
              }
            }
          ],
          "versions": [
            "v6.6.1",
            "v6.6",
            "v6.5",
            "v6.4.1",
            "v6.3.3",
            "v6.3.2",
            "v6.3.1",
            "v6.3",
            "v6.2.3",
            "v6.2.2",
            "v6.2.1",
            "v6.2",
            "v6.1",
            "v6.0.4",
            "v6.0.3",
            "v6.0.2",
            "v6.0.1",
            "v6.0",
            "v5.25.2",
            "v5.25.1",
            "v5.25",
            "v5.24",
            "v5.23",
            "v5.22",
            "v5.21",
            "v5.20.1",
            "v5.20",
            "v5.19.2",
            "v5.19.1",
            "v5.19",
            "v5.18.2",
            "v5.18.1",
            "v5.18",
            "v5.17",
            "v5.16.3",
            "v5.16.2",
            "v5.16.1",
            "v5.16",
            "v5.15",
            "v5.14",
            "v5.13",
            "v5.12.1",
            "v5.12",
            "v5.11",
            "v5.10.2",
            "v5.10.1",
            "v5.10",
            "v5.9",
            "v5.8.1",
            "v5.8",
            "v5.7",
            "v5.6",
            "v5.5.1",
            "v5.5",
            "v5.4",
            "v5.3.4",
            "v5.3.3",
            "v5.3.2",
            "v5.3.1",
            "v5.3",
            "v5.2",
            "v5.1",
            "v5.0",
            "v4.3.1",
            "v4.3",
            "v4.2.3",
            "v4.2.2",
            "v4.2.1",
            "v4.2",
            "v4.1.2",
            "v4.1.1",
            "v4.1",
            "v4.0",
            "v3.0",
            "v2.13.2",
            "v2.13.1",
            "v2.13",
            "v2.12",
            "v2.11.1",
            "v2.11",
            "v2.10",
            "v2.9.4",
            "v2.9.3",
            "v2.9.2",
            "v2.9.1",
            "v2.9",
            "v2.8",
            "v2.7.4",
            "v2.7.3",
            "v2.7.2",
            "v2.7.1",
            "v2.7",
            "v2.6.2",
            "v2.6.1",
            "v2.6",
            "v2.5",
            "v2.4.1",
            "v2.4",
            "v2.3.1",
            "v2.3",
            "v2.2",
            "v2.1",
            "v2.0",
            "v1.11.1",
            "v1.11",
            "v1.10.3",
            "v1.10.2",
            "v1.10.1",
            "v1.10",
            "v1.9",
            "v1.8",
            "v1.7",
            "v1.6",
            "v1.5.1",
            "v1.5",
            "v1.4",
            "v1.3.1",
            "v1.3",
            "v1.2.1",
            "v1.2",
            "v1.1",
            "v1.0"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-4891.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:29.911105490Z",
      "provider": "osv",
      "references": [
        "https://github.com/pi-hole/FTL/releases/tag/v6.6.2",
        "https://lists.thekelleys.org.uk/pipermail/dnsmasq-discuss/2026q2/018471.html",
        "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-4891.json",
        "https://thekelleys.org.uk/dnsmasq/CVE/",
        "https://www.kb.cert.org/vuls/id/471747",
        "https://access.redhat.com/errata/RHSA-2026:19158",
        "https://access.redhat.com/errata/RHSA-2026:19373",
        "https://access.redhat.com/errata/RHSA-2026:20589",
        "https://access.redhat.com/errata/RHSA-2026:34508",
        "https://access.redhat.com/errata/RHSA-2026:40762",
        "https://access.redhat.com/security/cve/CVE-2026-4891",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/4xxx/CVE-2026-4891.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-4891",
        "https://bugzilla.redhat.com/show_bug.cgi?id=2458517",
        "https://github.com/NixOS/nixpkgs/pull/519082",
        "https://github.com/NixOS/nixpkgs/pull/519093"
      ],
      "provider_metadata": {
        "cna_assigner": "certcc",
        "unresolved_ranges": [
          {
            "extracted_events": [
              {
                "range": [
                  {
                    "fixed": "2.92rel2"
                  }
                ],
                "source": "AFFECTED_FIELD",
                "strategy": "StandardRange"
              }
            ]
          }
        ],
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/4xxx/CVE-2026-4891.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-4891",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 496691,
  "published_at": "2026-05-11T16:47:33.202+00:00"
}