CVE-2026-44621

{
  "id": "CVE-2026-44621",
  "sourceIdentifier": "[email protected]",
  "published": "2026-07-22T14:17:18.913",
  "lastModified": "2026-10-24T13:10:00.147",
  "vulnStatus": "Analyzed",
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "With NLnet Labs Unbound up to and including version 1.25.1, applications using libunbound and configured with 'unwanted-reply-threshold', could eventually be abruptly terminated if the threshold is reached and libunbound needs to call 'libworker_alloc_cleanup' since the function is absent from the function call allow list. When an application using libunbound sets 'unwanted-reply-threshold' to any non-zero value and the iterator queries an authoritative that replies with enough wrong-transaction-ID UDP datagrams to cross the threshold, the 'libworker_alloc_cleanup' will eventually be called. Since the function is absent from the function call allow list, this leads to a fatal exit of libunbound and eventual termination of the embedding application.Unbound itself is not affected since its relevant function 'worker_alloc_cleanup' is registed in the allow list and proceeds to perform the documented cache flush."
    },
    {
      "lang": "es",
      "value": "Con NLnet Labs Unbound hasta la versión 1.25.1 inclusive, las aplicaciones que utilizan libunbound y están configuradas con ’unwanted-reply-threshold’ podrían terminar abruptamente si se alcanza el umbral y libunbound necesita llamar a ’libworker_alloc_cleanup’, ya que la función está ausente de la lista de permitidos de llamadas a funciones. Cuando una aplicación que utiliza libunbound establece ’unwanted-reply-threshold’ en cualquier valor distinto de cero y el iterador consulta a una autoridad que responde con suficientes datagramas UDP con ID de transacción incorrecto para superar el umbral, se llamará eventualmente a ’libworker_alloc_cleanup’. Dado que la función está ausente de la lista de permitidos de llamadas a funciones, esto provoca una salida fatal de libunbound y la terminación eventual de la aplicación que lo integra. Unbound en sí mismo no se ve afectado, ya que su función relevante ’worker_alloc_cleanup’ está registrada en la lista de permitidos y procede a realizar el vaciado de caché documentado."
    }
  ],
  "affected": [
    {
      "source": "[email protected]",
      "affectedData": [
        {
          "vendor": "NLnet Labs",
          "product": "Unbound",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "0",
              "lessThan": "1.25.2",
              "versionType": "semver",
              "status": "affected"
            }
          ]
        }
      ]
    }
  ],
  "metrics": {
    "cvssMetricV31": [
      {
        "source": "[email protected]",
        "type": "Secondary",
        "cvssData": {
          "version": "3.1",
          "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H",
          "baseScore": 5.9,
          "baseSeverity": "MEDIUM",
          "attackVector": "NETWORK",
          "attackComplexity": "HIGH",
          "privilegesRequired": "NONE",
          "userInteraction": "NONE",
          "scope": "UNCHANGED",
          "confidentialityImpact": "NONE",
          "integrityImpact": "NONE",
          "availabilityImpact": "HIGH"
        },
        "exploitabilityScore": 2.2,
        "impactScore": 3.6
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "timestamp": "2026-07-22T14:21:13.870660Z",
          "id": "CVE-2026-44621",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "role": "CISA Coordinator",
          "version": "2.0.3"
        }
      }
    ]
  },
  "weaknesses": [
    {
      "source": "[email protected]",
      "type": "Secondary",
      "description": [
        {
          "lang": "en",
          "value": "CWE-754"
        }
      ]
    }
  ],
  "configurations": [
    {
      "nodes": [
        {
          "operator": "OR",
          "negate": false,
          "cpeMatch": [
            {
              "vulnerable": true,
              "criteria": "cpe:2.3:a:nlnetlabs:unbound:*:*:*:*:*:*:*:*",
              "versionEndExcluding": "1.25.2",
              "matchCriteriaId": "9C01A425-F6D7-49A7-A72D-BF2159564DB6"
            }
          ]
        }
      ]
    }
  ],
  "references": [
    {
      "url": "https://www.nlnetlabs.nl/downloads/unbound/CVE-2026-44621.txt",
      "source": "[email protected]",
      "tags": [
        "Vendor Advisory"
      ]
    }
  ]
}