CVE-2026-32665

{
  "id": "CVE-2026-32665",
  "sourceIdentifier": "[email protected]",
  "published": "2026-07-22T14:17:18.193",
  "lastModified": "2026-10-24T13:10:00.147",
  "vulnStatus": "Analyzed",
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In NLnet Labs Unbound 1.22.0 up to and including 1.25.1, when downstream DNS-over-QUIC (DoQ) is enabled, the first two bidirectional streams on a new QUIC connection (stream_id 0 and 4) bypass the per-stream 'quic-size' gate entirely, and large input buffers are allocated later, after only the 2-byte length prefix has been received from the initial streams. As a result, a remote client can make Unbound exceed the configured 'quic-size' limit with low-cost input. Using only one connection and two streams, each sending a declared 65535-byte length prefix and then holding the streams open, a client can already trivially make Unbound roughly allocate double that amount. This is a remote availability issue / memory-accounting bypass in the downstream DoQ implementation that leads to denial of service for new DoQ clients. This vulnerability needs Unbound to be compiled with DoQ support ('--with-libngtcp2') and the 'quic-port' to be configured for the listening interfaces."
    },
    {
      "lang": "es",
      "value": "En NLnet Labs Unbound 1.22.0 hasta la versión 1.25.1 inclusive, cuando DNS-over-QUIC (DoQ) descendente está habilitado, los dos primeros flujos bidireccionales en una nueva conexión QUIC (stream_id 0 y 4) omiten completamente la ’puerta’ ’quic-size’ por flujo, y se asignan grandes búferes de entrada más tarde, después de que solo se haya recibido el prefijo de longitud de 2 bytes de los flujos iniciales. Como resultado, un cliente remoto puede hacer que Unbound exceda el límite ’quic-size’ configurado con entrada de bajo costo. Usando solo una conexión y dos flujos, cada uno enviando un prefijo de longitud declarado de 65535 bytes y luego manteniendo los flujos abiertos, un cliente ya puede hacer que Unbound asigne aproximadamente el doble de esa cantidad de forma trivial. Esto es un problema de disponibilidad remota / una omisión de contabilidad de memoria en la implementación descendente de DoQ que conduce a la denegación de servicio para nuevos clientes DoQ. Esta vulnerabilidad requiere que Unbound sea compilado con soporte DoQ (’--with-libngtcp2’) y que el puerto ’quic-port’ sea configurado para las interfaces de escucha."
    }
  ],
  "affected": [
    {
      "source": "[email protected]",
      "affectedData": [
        {
          "vendor": "NLnet Labs",
          "product": "Unbound",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "1.22.0",
              "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:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
          "baseScore": 7.5,
          "baseSeverity": "HIGH",
          "attackVector": "NETWORK",
          "attackComplexity": "LOW",
          "privilegesRequired": "NONE",
          "userInteraction": "NONE",
          "scope": "UNCHANGED",
          "confidentialityImpact": "NONE",
          "integrityImpact": "NONE",
          "availabilityImpact": "HIGH"
        },
        "exploitabilityScore": 3.9,
        "impactScore": 3.6
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "timestamp": "2026-07-22T14:31:54.691586Z",
          "id": "CVE-2026-32665",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "yes"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "role": "CISA Coordinator",
          "version": "2.0.3"
        }
      }
    ]
  },
  "weaknesses": [
    {
      "source": "[email protected]",
      "type": "Secondary",
      "description": [
        {
          "lang": "en",
          "value": "CWE-1284"
        }
      ]
    }
  ],
  "configurations": [
    {
      "nodes": [
        {
          "operator": "OR",
          "negate": false,
          "cpeMatch": [
            {
              "vulnerable": true,
              "criteria": "cpe:2.3:a:nlnetlabs:unbound:*:*:*:*:*:*:*:*",
              "versionStartIncluding": "1.22.0",
              "versionEndExcluding": "1.25.2",
              "matchCriteriaId": "0C48102E-1D81-4A87-898D-F1CE83C78D26"
            }
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  ],
  "references": [
    {
      "url": "https://www.nlnetlabs.nl/downloads/unbound/CVE-2026-32665.txt",
      "source": "[email protected]",
      "tags": [
        "Vendor Advisory"
      ]
    }
  ]
}