CVE-2026-55367

{
  "etk_id": "ETK-2026-2559",
  "cve_id": "CVE-2026-55367",
  "display_id": "CVE-2026-55367",
  "ghsa_id": "GHSA-q342-qp8v-p44c",
  "euvd_id": null,
  "status": "published",
  "anchor_state": "awaiting_cve",
  "title": "H2O CONNECT-UDP buffering denial of service",
  "summary": "H2O instances using `proxy.connect-udp` may retain excessive data for malformed, unfinished CONNECT-UDP Capsule messages. A remote client that can make CONNECT-UDP requests may exhaust memory and interrupt service; deployments without that feature enabled are not described as affected.",
  "mitigation": "Upgrade h2o to commits 4212ce1 and above or later.",
  "vendor": "other",
  "product": "other:h2o",
  "affected": [
    {
      "affected_notes": [
        "commits up to 7f76f0d"
      ],
      "affected_ranges": [],
      "ecosystem": "other",
      "fixed_versions": [
        "commits 4212ce1 and above"
      ],
      "package_name": "h2o",
      "purl": null
    }
  ],
  "cwes": null,
  "cvss_score": 7.5,
  "cvss_src": "cna_vendor",
  "cvss_vector": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
  "epss_score": null,
  "epss_percentile": null,
  "epss_asof": null,
  "automation": "deterministic",
  "check": false,
  "check_confidence_basis": null,
  "exploit": false,
  "pipeline_minutes": 17.623860783333335,
  "t0_at": null,
  "signals": {
    "trigger_signal": {
      "at": "2026-10-23T08:19:11+00:00",
      "days": -1.5817674433333333,
      "is_lower_bound": true,
      "measured_at": "2026-10-24T22:16:55.731119+00:00",
      "url": "https://github.com/h2o/h2o/security/advisories/GHSA-q342-qp8v-p44c"
    }
  }
}