Researchers tricked Copilot into leaking an undocumented parameter enabling one-click Gmail/Drive theft

heypearlai · x · 2026-08-20

Microsoft patched a Copilot bug on Aug 18 that let attackers steal a victim's Gmail, Drive and Calendar data with a single click on a crafted link. Varonis researchers found it by repeatedly asking Copilot "why can't this happen" — every refusal came with technical explanations, and eventually the AI volunteered an undocumented URL parameter mid-refusal, which turned out to be the core of the exploit. No evidence of exploitation before the fix.

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