{
  "id": 19833612,
  "title": "Windows 0-day dropped by disgruntled researcher hands hackers System rights",
  "url": "https://urgent.news/2026/11/13/windows-0-day-dropped-by-disgruntled-researcher-hands-hackers-system",
  "topic": "tech",
  "section": "Tech",
  "published": "2026-11-13T16:26:32.000Z",
  "source": {
    "name": "Ars Technica",
    "slug": "ars-technica",
    "url": "https://arstechnica.com/security/2026/11/windows-0-day-dropped-by-disgruntled-researcher-hands-hackers-system-rights/"
  },
  "original_language": "en",
  "account": "Nightmare Eclipse, a researcher known for a contentious relationship with Microsoft, has recently revealed a new Windows zero-day vulnerability named SignDrop. This flaw allows local users to gain complete System rights on certain Windows versions. The vulnerability lies within the Common Log File System, a general-purpose logging service utilized by software clients operating in user-mode or kernel-mode. By manipulating a privileged process like Windows Defender into opening a specially crafted Common Log File System (CLFS) container, an attacker with regular user privileges can abuse the elevated file creation to attain System-level access. Essentially, the attack exploits the relationship between the CLFS, Windows Defender, and Windows file permissions. The exploit leverages Windows Defender to open a log file generated by a standard user by invoking ServerMpUpdateEngineSignature, a legitimate Defender function used for processing antivirus signature updates.",
  "summary": "\"SignDrop\" exploit lets local users gain all-powerful System rights.",
  "key_points": [],
  "editors_take": null,
  "illustration": null,
  "coverage": {
    "outlets": 1,
    "also_reported_by": []
  },
  "ai_generated": true,
  "disclaimer": "Summaries, key points and the editor’s take are written by software from other outlets’ reporting and may contain errors — always check the linked original."
}