Rein Security Raises $25 Million to Secure AI Agents

Cybersecurity firm Rein Security has secured $25 million in Series A funding, less than a year after its initial seed round. This latest investment brings the company's total funding to $35 million and arrives as the security of AI agents becomes a critical focus in the Israeli cybersecurity market. The funding round was co-led by Glilot Capital and Sienna Venture Capital, with participation from Corner Ventures, Atlacle, and RNP Capital Advisors. Rein Security, which currently employs 31 people and operates from Tel Aviv and New York, plans to use the new capital to expand its research and development, hire more staff, and grow its commercial operations.

Since launching its product in early 2026, Rein Security reports an eightfold increase in revenue and a fivefold expansion in its customer base. Its platform is already used by thousands of AI agents performing millions of actions within organizations, counting clients such as Dun & Bradstreet, Lemonade, Flex, and Swimlane. The company's approach addresses the evolving role of AI in businesses, where new AI agents are granted permissions to access sensitive information, execute code, and perform business operations, unlike older chatbots that primarily generated text.

Rein Security's platform provides a real-time protection layer that monitors the AI agent's code, resource access, and requested actions. It allows organizations to pre-define which actions are permissible and which should be blocked, offering direct control within the AI's runtime environment. This contrasts with systems that route all AI activity through a central gateway. The company is operating in a rapidly growing market, with Gartner projecting the AI security market to reach approximately $4.8 billion in 2027, a significant increase from previous years.

The burgeoning AI security sector is attracting substantial investment, with several Israeli companies focusing on areas like permission management, agent behavior monitoring, and AI-driven attack defense. Companies like Symphony and Hush Security have recently raised significant funding for platforms managing AI agent access to sensitive data and identity management, respectively. Rein Security's specific focus is on securing AI agents during the execution of their tasks, having demonstrated how vulnerabilities in AI agents can be exploited and how its system can detect and block malicious actions in real-time.