AI security platform Rein Security completes $25 million Series A funding round, led by Sienna Venture Capital, among others.

On October 8 that, according to pulse2, AI-native security platform Rein Security has secured $25 million in Series A funding, bringing its total fundraising to $35 million. The round was co-led by Glilot Capital and Sienna Venture Capital, with participation from Corner Ventures, Atlacle, and RNP Capital Advisors.

The company helps businesses secure on-premises AI agents and defend against AI-driven attacks by monitoring code executed by AI agents and the resources they access, enabling real-time governance and control. The new capital will accelerate product development, expand AI security research, and support global hiring.