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Rein Security raises $25 million to guard AI agents
The Tel Aviv and New York start-up watches agents as they act and blocks harmful steps, and says revenue is up eightfold this year.
Rein Security, a start-up based in Tel Aviv and New York, raised $25 million in a Series A round announced on 8 October 2026, taking its total funding to $35 million, SecurityWeek reports. Glilot Capital and Sienna Venture Capital co-led, with Corner Ventures, Atlacle and RNP Capital Advisors joining.
Rein watches AI agents at the moment they act, holds each to its assigned role and blocks harmful steps before they run, without routing data through a gateway, the company says. It reports eightfold revenue growth and five times as many customers since its January 2026 launch, and says it already secures thousands of agents, SecurityWeek reports.
Rein argues, SiliconANGLE reports, that agents bring two new risks: a company’s own agents taking harmful actions on instructions from other systems, and attackers’ agents probing defences around the clock. The money goes to product work, agent security research and hiring.
Every agent given access to customer data or payments needs a check on what it does next, and investors are now funding that check as its own product.
Sources
- SecurityWeek: Rein Security Raises $25 Million to Guard AI Agents at Runtime. Checked
- SiliconANGLE: Rein Security raises $25M to rein in insecure AI agents. Checked
- Rein Security: Rein Security Series A. Checked
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