CVE-2026-44434

{
  "id": "CVE-2026-44434",
  "sourceIdentifier": "[email protected]",
  "published": "2026-07-16T23:16:16.870",
  "lastModified": "2026-10-24T20:10:00.137",
  "vulnStatus": "Analyzed",
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "Quicly is an IETF QUIC protocol implementation intended primarily for use within the H2O HTTP server. Prior to commit dccf5d4, Quicly was vulnerable to stateless reset injection through lack of packet entry validation. The QUIC protocol is designed to withstand packet injection attacks, once the handshake is complete. Only packets that carry some secret patterns are considered as stateless resets. Quicly allows the peer to share up to 4 such patterns per connection. However, until now, it failed to determine which of the 4 slots that it uses to retain the secret patterns contains a valid entry. As the slots are zero-initialized, the failure meant that, unless the peer advertised 4 of such patterns, an all-zero pattern was treated as a stateless reset.In effect, this allowed an on-path attacker to reset QUIC connections governed by Quicly. This issue has been fixed by commit dccf5d4."
    },
    {
      "lang": "es",
      "value": "Quicly es una implementación del protocolo QUIC de la IETF destinada principalmente para su uso dentro del servidor HTTP H2O. Antes del commit dccf5d4, Quicly era vulnerable a la inyección de restablecimiento sin estado debido a la falta de validación de entrada de paquetes. El protocolo QUIC está diseñado para resistir ataques de inyección de paquetes, una vez que el handshake está completo. Solo los paquetes que contienen ciertos patrones secretos se consideran restablecimientos sin estado. Quicly permite al par compartir hasta 4 de dichos patrones por conexión. Sin embargo, hasta ahora, no lograba determinar cuál de las 4 ranuras que utiliza para retener los patrones secretos contenía una entrada válida. Como las ranuras se inicializan a cero, el fallo significaba que, a menos que el par anunciara 4 de dichos patrones, un patrón de todo ceros era tratado como un restablecimiento sin estado. En efecto, esto permitía a un atacante en la ruta restablecer conexiones QUIC gobernadas por Quicly. Este problema ha sido solucionado por el commit dccf5d4."
    }
  ],
  "affected": [
    {
      "source": "[email protected]",
      "affectedData": [
        {
          "vendor": "h2o",
          "product": "quicly",
          "versions": [
            {
              "version": "< dccf5d4",
              "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:L",
          "baseScore": 5.3,
          "baseSeverity": "MEDIUM",
          "attackVector": "NETWORK",
          "attackComplexity": "LOW",
          "privilegesRequired": "NONE",
          "userInteraction": "NONE",
          "scope": "UNCHANGED",
          "confidentialityImpact": "NONE",
          "integrityImpact": "NONE",
          "availabilityImpact": "LOW"
        },
        "exploitabilityScore": 3.9,
        "impactScore": 1.4
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "timestamp": "2026-07-18T03:21:11.398981Z",
          "id": "CVE-2026-44434",
          "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-345"
        },
        {
          "lang": "en",
          "value": "CWE-665"
        }
      ]
    }
  ],
  "configurations": [
    {
      "nodes": [
        {
          "operator": "OR",
          "negate": false,
          "cpeMatch": [
            {
              "vulnerable": true,
              "criteria": "cpe:2.3:a:h2o:quicly:*:*:*:*:*:*:*:*",
              "versionEndExcluding": "2026-05-29",
              "matchCriteriaId": "FD025CC7-B866-4C0E-873A-86908DC9E6BD"
            }
          ]
        }
      ]
    }
  ],
  "references": [
    {
      "url": "https://github.com/h2o/quicly/commit/dccf5d4579c7ae9dd6e8f90c36d52e311bb60710",
      "source": "[email protected]",
      "tags": [
        "Patch"
      ]
    },
    {
      "url": "https://github.com/h2o/quicly/security/advisories/GHSA-899f-49jq-pfh8",
      "source": "[email protected]",
      "tags": [
        "Vendor Advisory"
      ]
    }
  ]
}