{
  "affected": [
    {
      "ranges": [
        {
          "database_specific": {
            "source": "REFERENCES"
          },
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "8dc37cb1e6171f7f772667618ea440696fed82c3"
            }
          ],
          "repo": "https://github.com/h2o/h2o",
          "type": "GIT"
        }
      ]
    }
  ],
  "aliases": [
    "GHSA-w68q-rqwx-7wvq"
  ],
  "database_specific": {
    "cna_assigner": "GitHub_M",
    "cwe_ids": [
      "CWE-125",
      "CWE-170"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/44xxx/CVE-2026-44452.json",
    "unresolved_ranges": [
      {
        "extracted_events": [
          {
            "fixed": "8dc37cb"
          }
        ],
        "source": "AFFECTED_FIELD"
      }
    ]
  },
  "details": "h2o is an HTTP server with support for HTTP/1.x, HTTP/2 and HTTP/3. Prior to commit 8dc37cb, when h2o receives a ClientHello message over TLS or QUIC and it contains a zero-length SNI extension, the h2o server runs over the zero-length hostname while trying to copy the hostname, assuming that it is NULL-terminated. This is a potential denial-of-service attack vector in sense that it might trigger segmentation violation. This issue has been fixed by commit 8dc37cb.",
  "id": "CVE-2026-44452",
  "modified": "2026-07-19T03:30:51.882198088Z",
  "published": "2026-07-16T22:54:42.914Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/44xxx/CVE-2026-44452.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/h2o/h2o/security/advisories/GHSA-w68q-rqwx-7wvq"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-44452"
    },
    {
      "type": "FIX",
      "url": "https://github.com/h2o/h2o/commit/8dc37cb1e6171f7f772667618ea440696fed82c3"
    }
  ],
  "schema_version": "1.8.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "h2o is vulnerable to heap overrun"
}