Browser Agents Need Strict Session Boundaries to Prevent Automation Security Failures

Browser automation creates persistent sessions that retain cookies, storage, tabs, and incomplete actions even after an AI agent loses context, posing risks that API-only systems typically avoid. Security-focused developers recommend treating every browser session as an isolated, expiring execution unit with a defined contract specifying its owner, purpose, permitted sites, and deadline. Each browser worker should use a disposable profile per workflow rather than a shared or human-linked Chrome profile, which may carry unrelated credentials and extensions. If a worker crashes mid-action, the replacement should mark the step as unknown and verify via a read-only check before retrying, since a click or timeout alone cannot confirm whether a server-side effect occurred. Revocation and authorization logic should be enforced at the browser worker or policy layer, not left to the agent to interpret through instructions or page content.