{
  "affected": [
    {
      "affectedData": [
        {
          "product": "quicly",
          "vendor": "h2o",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c dccf5d4"
            }
          ]
        }
      ],
      "source": "security-advisories@github.com"
    }
  ],
  "configurations": [
    {
      "nodes": [
        {
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:h2o:quicly:*:*:*:*:*:*:*:*",
              "matchCriteriaId": "FD025CC7-B866-4C0E-873A-86908DC9E6BD",
              "versionEndExcluding": "2026-05-29",
              "vulnerable": true
            }
          ],
          "negate": false,
          "operator": "OR"
        }
      ]
    }
  ],
  "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 implementaci\u00f3n 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 inyecci\u00f3n de restablecimiento sin estado debido a la falta de validaci\u00f3n de entrada de paquetes. El protocolo QUIC est\u00e1 dise\u00f1ado para resistir ataques de inyecci\u00f3n de paquetes, una vez que el handshake est\u00e1 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 conexi\u00f3n. Sin embargo, hasta ahora, no lograba determinar cu\u00e1l de las 4 ranuras que utiliza para retener los patrones secretos conten\u00eda una entrada v\u00e1lida. Como las ranuras se inicializan a cero, el fallo significaba que, a menos que el par anunciara 4 de dichos patrones, un patr\u00f3n de todo ceros era tratado como un restablecimiento sin estado. En efecto, esto permit\u00eda a un atacante en la ruta restablecer conexiones QUIC gobernadas por Quicly. Este problema ha sido solucionado por el commit dccf5d4."
    }
  ],
  "id": "CVE-2026-44434",
  "lastModified": "2026-10-24T20:10:00.137",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "LOW",
          "baseScore": 5.3,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "NONE",
          "integrityImpact": "NONE",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L",
          "version": "3.1"
        },
        "exploitabilityScore": 3.9,
        "impactScore": 1.4,
        "source": "security-advisories@github.com",
        "type": "Secondary"
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-44434",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "yes"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2026-07-18T03:21:11.398981Z",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2026-07-16T23:16:16.870",
  "references": [
    {
      "source": "security-advisories@github.com",
      "tags": [
        "Patch"
      ],
      "url": "https://github.com/h2o/quicly/commit/dccf5d4579c7ae9dd6e8f90c36d52e311bb60710"
    },
    {
      "source": "security-advisories@github.com",
      "tags": [
        "Vendor Advisory"
      ],
      "url": "https://github.com/h2o/quicly/security/advisories/GHSA-899f-49jq-pfh8"
    }
  ],
  "sourceIdentifier": "security-advisories@github.com",
  "vulnStatus": "Analyzed",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-345"
        },
        {
          "lang": "en",
          "value": "CWE-665"
        }
      ],
      "source": "security-advisories@github.com",
      "type": "Secondary"
    }
  ]
}