CVE-2026-55368

{
  "etk_id": "ETK-2026-2550",
  "cve_id": "CVE-2026-55368",
  "display_id": "CVE-2026-55368",
  "ghsa_id": "GHSA-m998-r5ww-rqjf",
  "euvd_id": null,
  "status": "published",
  "anchor_state": "awaiting_cve",
  "title": "Out-of-bounds write in H2O access-log formatting",
  "summary": "H2O instances using custom access-log formats are affected by an out-of-bounds write in the access-log formatter. A request reaching an affected formatting path can crash the server; impact beyond a crash has not been established.",
  "mitigation": "Upgrade h2o to commits 48b7ae1 and above or later.",
  "vendor": "other",
  "product": "other:h2o",
  "affected": [
    {
      "affected_notes": [
        "commits up to 4212ce1"
      ],
      "affected_ranges": [],
      "ecosystem": "other",
      "fixed_versions": [
        "commits 48b7ae1 and above"
      ],
      "package_name": "h2o",
      "purl": null
    }
  ],
  "cwes": null,
  "cvss_score": 8.1,
  "cvss_src": "cna_vendor",
  "cvss_vector": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H",
  "epss_score": null,
  "epss_percentile": null,
  "epss_asof": null,
  "automation": "contextual",
  "check": false,
  "check_confidence_basis": null,
  "exploit": false,
  "pipeline_minutes": 17.11939875,
  "t0_at": null,
  "signals": {
    "trigger_signal": {
      "at": "2026-10-23T08:26:14+00:00",
      "days": -1.575659667523148,
      "is_lower_bound": true,
      "measured_at": "2026-10-24T22:15:11.054519+00:00",
      "url": "https://github.com/h2o/h2o/security/advisories/GHSA-m998-r5ww-rqjf"
    }
  }
}