bind9 — security advisory

{
  "id": "894a392fb7c3a01cb4b81c2f79dd169756787929710f9a7bfca5c557e71199fc",
  "url": "https://osv.dev/vulnerability/DEBIAN-CVE-2025-40777",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "DEBIAN-CVE-2025-40777",
    "summary": "If a `named` caching resolver is configured with `serve-stale-enable` `yes`, and with `stale-answer-client-timeout` set to `0` (the only allowable value other than `disabled`), and if the resolver, in the process of resolving a query, encounters a CNAME chain involving a specific combination of cached or authoritative records, the daemon will abort with an assertion failure. This issue affects BIND 9 versions 9.20.0 through 9.20.10, 9.21.0 through 9.21.9, and 9.20.9-S1 through 9.20.10-S1.",
    "evidence": "osv:DEBIAN-CVE-2025-40777",
    "products": [
      {
        "name": {
          "value": "bind9",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "1:9.20.11-1",
            "evidence": "/affected/0/ranges"
          }
        ],
        "affected_versions": []
      },
      {
        "name": {
          "value": "bind9",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "1:9.20.11-1",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "high",
    "structured": {
      "id": "DEBIAN-CVE-2025-40777",
      "aliases": [
        "DEBIAN-CVE-2025-40777"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "1:9.20.11-1"
                }
              ]
            }
          ],
          "package": {
            "name": "bind9",
            "purl": "pkg:deb/debian/bind9?arch=source&distro=trixie",
            "ecosystem": "Debian:13"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2025-40777.json"
          },
          "ecosystem_specific": {
            "urgency": "not yet assigned"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "1:9.20.11-1"
                }
              ]
            }
          ],
          "package": {
            "name": "bind9",
            "purl": "pkg:deb/debian/bind9?arch=source&distro=forky",
            "ecosystem": "Debian:14"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2025-40777.json"
          },
          "ecosystem_specific": {
            "urgency": "not yet assigned"
          }
        }
      ],
      "modified": "2026-10-23T13:00:06.546150508Z",
      "provider": "osv",
      "upstream": [
        "CVE-2025-40777"
      ],
      "references": [
        "https://security-tracker.debian.org/tracker/CVE-2025-40777"
      ]
    },
    "related_cves": [
      {
        "value": "CVE-2025-40777",
        "evidence": "/upstream"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 412820,
  "published_at": "2025-07-16T18:15:24.77+00:00"
}