Rein Security raises $25M to secure AI agents

Rein Security has raised $25 million in a Series A round led by Glilot Capital and others, bringing its total funding to $35 million. The startup addresses two AI agent security threats: protecting enterprises' own autonomous agents from taking harmful actions, and defending IT infrastructure from hacker-controlled agents. Its platform deploys as a lightweight sidecar at runtime, establishing behavioral baselines for each agent and blocking only malicious actions without halting workflows. Customers include Flex, Swimlane, Lemonade, and Dun & Bradstreet, and the company has grown its customer base more than fivefold this year.