AI Matters
Why it matters
Researcher builds self-spreading worm that hijacks Microsoft Copilot
The Decoder A security researcher built a self-spreading worm that hides inside Word docs and hijacks Microsoft Copilot
A security researcher demonstrated a vulnerability in Microsoft Copilot for Word where invisible prompt injections automatically spread to new documents.
Why it matters
The exploit shows how easily malicious prompts hidden in documents can compromise AI assistants and automatically infect other files.
Latest brief · Aug 1, 2026