A proof-of-concept prompt injection caused Comet to access authenticated account data, read a Gmail one-time password and exfiltrate the information without further user input.

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Location PART 1 - TONS OF PUNKS, ONE BIG JERK CHAPTER 2: NO MOAT IN BLOAT Bug Hunt or Witch Hunt?

"A proof-of-concept prompt injection caused Comet to access authenticated account data, read a Gmail one-time password and exfiltrate the information without further user input."

Brave's demonstration had malicious webpage instructions make Comet retrieve account details, read an OTP from Gmail and send the information back through a Reddit comment.

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Source title Agentic Browser Security: Indirect Prompt Injection in Perplexity Comet

Source authors Artem Chaikin, Shivan Kaul Sahib

Source year 2025

Confidence high

Importance high