{
  "affected": [
    {
      "ranges": [
        {
          "database_specific": {
            "extracted_events": [
              {
                "introduced": "2.0.0-beta.4"
              },
              {
                "fixed": "2.0.1-rc.18"
              },
              {
                "introduced": "0"
              }
            ],
            "source": [
              "AFFECTED_FIELD",
              "DESCRIPTION"
            ]
          },
          "events": [
            {
              "introduced": "62356d7964d2640b6bf7bbba457732fe944ed618"
            },
            {
              "fixed": "cb70e1ba513be827bb3698127bb7d06467412911"
            }
          ],
          "repo": "https://github.com/h3js/h3",
          "type": "GIT"
        }
      ]
    }
  ],
  "aliases": [
    "GHSA-q5pr-72pq-83v3"
  ],
  "database_specific": {
    "cna_assigner": "VulnCheck",
    "cwe_ids": [
      "CWE-400"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/86xxx/CVE-2026-86250.json"
  },
  "details": "h3 versions before 2.0.1-rc.18 fail to validate the chunk count parsed from user-controlled cookie values in setChunkedCookie() and deleteChunkedCookie() functions. Attackers can send a crafted cookie header with an extremely large chunk count to trigger an O(n²) cleanup loop that hangs the server process.",
  "id": "CVE-2026-86250",
  "modified": "2026-09-10T03:31:03.616866175Z",
  "published": "2026-09-06T12:00:26.211Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/86xxx/CVE-2026-86250.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/h3js/h3/security/advisories/GHSA-q5pr-72pq-83v3"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-86250"
    },
    {
      "type": "ADVISORY",
      "url": "https://www.vulncheck.com/advisories/h3-before-2.0.1-rc.18-denial-of-service-via-unbounded-chunked-cookie"
    }
  ],
  "schema_version": "1.9.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "h3 before 2.0.1-rc.18 Denial of Service via Unbounded Chunked Cookie"
}