Prompt injections in agentic browsers

Originally published at https://shivankaul.com/blog/prompt-injections-in-agentic-browsers . In August 2025 we found, responsibly disclosed and wrote about an indirect prompt injection attack in Perplexity’s Comet browser. The attack exploited agent-controlled browsing in Comet. We followed this up with several new disclosures which proved that this wasn’t a one-off case of bad security practices…