CVE-2026-121437

{
  "etk_id": "ETK-2026-3374",
  "cve_id": "CVE-2026-121437",
  "display_id": "CVE-2026-121437",
  "ghsa_id": "GHSA-xr4w-hw52-gjv9",
  "euvd_id": "EUVD-2026-115859",
  "status": "published",
  "anchor_state": "anchored",
  "title": "Quadratic parsing denial of service in Mistune",
  "summary": "Mistune versions 3.3.0 through 3.3.3 are affected by excessive CPU use during emphasis-delimiter parsing. A remote attacker can cause worker stalls or reduced availability by supplying specially formed Markdown. Exploitation requires the application to parse Markdown from an attacker-controlled source.",
  "mitigation": "Upgrade the mistune package to version 3.3.4 or later. Until upgraded, limit or disable processing of untrusted Markdown and apply request size and execution-time limits.",
  "vendor": "lepture",
  "product": "mistune",
  "affected": [
    {
      "affected_notes": [],
      "affected_ranges": [
        ">= 3.3.0, < 3.3.4"
      ],
      "ecosystem": null,
      "fixed_versions": [
        "3.3.4"
      ],
      "package_name": "mistune",
      "purl": null
    }
  ],
  "cwes": [
    407
  ],
  "cvss_score": 8.7,
  "cvss_src": "cna_vendor",
  "cvss_vector": "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",
  "epss_score": null,
  "epss_percentile": null,
  "epss_asof": null,
  "automation": "contextual",
  "check": false,
  "check_confidence_basis": null,
  "exploit": false,
  "pipeline_minutes": 16.74700895,
  "t0_at": "2026-11-03T14:28:29.178000+00:00",
  "signals": {
    "trigger_signal": {
      "at": "2026-11-03T14:28:29.178000+00:00",
      "days": 0,
      "is_lower_bound": false,
      "measured_at": "2026-11-03T14:28:29.178000+00:00",
      "url": "https://www.cve.org/CVERecord?id=CVE-2026-121437"
    }
  }
}