Agentic Browser Same-Origin Risk Checklist

4 of 7 studied browsers got this wrong — check yours.

A University of Washington research team studying seven popular agentic browsers found that four create ways for a malicious actor to bypass the same-origin policy, enabling cross-site data exfiltration through prompt injection and memory poisoning — a foundational web security assumption that agentic browser architecture can undermine if not deliberately designed against. This checklist is built for teams building on, evaluating, or deploying agentic browser technology, covering the architectural controls that actually address this: explicit cross-origin re-authorization, scoped DOM and credential access, origin-level action logging, and an explicit exclusion list for the most sensitive origins.

• →Built directly around the documented UW research finding 4 of 7 agentic browsers bypass same-origin isolation
• →Weights explicit cross-origin re-authorization and scoped DOM access as the top architectural defenses
• →Distinct from the consumer-facing privacy checklist — this targets teams building/deploying the technology
• →Includes vendor disclosure review and independent testing as verification steps beyond trusting vendor claims
• →Watermarked by Cikal Studio Labs · Works on any device, no install required