{
  "cveId": "CVE-2026-86431",
  "url": "https://patchblox.com/security/cve/CVE-2026-86431",
  "summary": "CVE-2026-86431 is fixed in php-league-commonmark on 1 platform by DEBIAN-CVE-2026-86431 (version 2.10.0-1), released September 8, 2026. It is not reported as exploited. Patch Radar priority: Routine.",
  "title": "php-league-commonmark: league/commonmark (thephpleague/commonmark) versions \u003E= 2.7.0 and \u003C 2.9.1 contain a cross-site scripting vulnerabilit...",
  "description": "league/commonmark (thephpleague/commonmark) versions \u003E= 2.7.0 and \u003C 2.9.1 contain a cross-site scripting vulnerability in the AttributesExtension. Prefixing an attribute name with a single U\u002B000C form feed byte (e.g. {\\x0Conclick=\u0022alert(1)\u0022}) bypasses the AttributesHelper::filterAttributes() \u0027on*\u0027 event-handler filter because PHP\u0027s trim() does not strip U\u002B000C, causing the attribute to be written verbatim into the output where browsers parse it as a genuine event handler. The same prefix also defeats the allow_unsafe_links check, allowing javascript: URIs through href/src attributes even when allow_unsafe_links is false. Exploitation requires processing untrusted Markdown with the AttributesExtension enabled; the injected script executes when the rendered HTML is viewed. Fixed in 2.9.1.",
  "published": "2026-09-07T13:20:42Z",
  "severity": "",
  "epss": 0.00388,
  "epssPercentile": 0.33164,
  "priority": "Routine",
  "priorityTier": 4,
  "exploited": false,
  "vendorExploited": false,
  "disclosed": false,
  "fixes": [
    {
      "platform": "linux",
      "product": "php-league-commonmark",
      "release": "Debian 14",
      "fixedVersion": "2.10.0-1",
      "fix": "DEBIAN-CVE-2026-86431",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2026-86431",
      "released": "2026-09-08T02:27:47Z"
    }
  ],
  "noFixYet": [],
  "dataAsOf": "2026-11-09T13:31:49Z",
  "attribution": {
    "text": "Data: Patchblox Patch Radar",
    "url": "https://patchblox.com/security/patch-radar",
    "terms": "https://patchblox.com/security/patch-radar/use-the-data"
  }
}