CVE-2026-44435

{
  "id": "CVE-2026-44435",
  "sourceIdentifier": "[email protected]",
  "published": "2026-07-16T23:16:17.010",
  "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 937d0e9, an assertion failure is raised when the total number of valid handshake messages received over a CRYPTO stream of a single packet number space exceeds 32KB, causing a Denial of Service. This issue has been fixed by commit 937d0e9."
    },
    {
      "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 937d0e9, se produce un fallo de aserción cuando el número total de mensajes de handshake válidos recibidos a través de un flujo CRYPTO de un único espacio de número de paquete excede los 32KB, causando una denegación de servicio. Este problema ha sido solucionado por el commit 937d0e9."
    }
  ],
  "affected": [
    {
      "source": "[email protected]",
      "affectedData": [
        {
          "vendor": "h2o",
          "product": "quicly",
          "versions": [
            {
              "version": "< 937d0e9",
              "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": "2026-07-17T13:02:47.698484Z",
          "id": "CVE-2026-44435",
          "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-400"
        },
        {
          "lang": "en",
          "value": "CWE-617"
        }
      ]
    }
  ],
  "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/937d0e9e7c669fc2bee4920632ab6aaac60e4d81",
      "source": "[email protected]",
      "tags": [
        "Patch"
      ]
    },
    {
      "url": "https://github.com/h2o/quicly/security/advisories/GHSA-2cw9-5673-73gv",
      "source": "[email protected]",
      "tags": [
        "Vendor Advisory"
      ]
    }
  ]
}