# Rein Security Raises $25M for AI Agent Security

> Rein Security secures $25M to protect AI agents from attacks as enterprises deploy more autonomous systems.
- Title: Rein Security Raises $25M for AI Agent Security · AI Insider
- Summary: Rein Security secures $25M to protect AI agents from attacks as enterprises deploy more autonomous systems. Rein Security raised $25 million in Series A…
- Keywords: breaking, rein security, ai agents, series a funding, glilot capital, sienna venture capital, corner ventures, atlacle, rnp capital advisors, dun bradstreet, lemonade, ai security
- Source: AI Insider — https://theaiinsider.tech/2026/10/09/rein-security-raises-25m-to-secure-the-ai-agents-enterprises-build-and-stop-the-ones-that-attack-them
- Author: James Dargan
- Published: 2026-10-09T16:18:05+00:00
- Read time: 1 min
- Topics: breaking, rein security, ai agents, series a funding, glilot capital, sienna venture capital, corner ventures, atlacle, rnp capital advisors, dun bradstreet, lemonade, ai security
## Rein Security Raises $25M
Rein Security, an AI-native runtime security platform for enterprises, has secured $25 million in Series A financing co-led by Glilot Capital and Sienna Venture Capital.
## Total Funding $35M
The round brings Rein Security’s total funding to $35 million with participation from Corner Ventures, Atlacle and RNP Capital Advisors.
## Patented Sidecar Technology
Rein’s platform uses patented sidecar technology that operates where AI agents execute actions to provide real-time visibility and guardrails.
## 8x Revenue Growth
Since its January 2026 launch, Rein has grown revenue 8x and its customer base 5x.
## Key Customers
Rein secures AI agents for Dun & Bradstreet and Lemonade, supporting over three million customers and 240,000 users.
## Security Challenges
Enterprises face two security challenges: securing agents they build while defending against increasingly capable AI-driven attacks.
## Gartner Projections
Gartner projects the ai security market to reach $4.8 billion in 2027, up 68.7% from 2026, and $7.7 billion by 2028.
## Real-World Threats
Rein detected a prompt injection attack that redirected an agent outside its intended role before causing damage.
## Investor Support
Glilot Capital and Sienna Venture Capital back Rein’s platform as the solution for the growing agent economy.
## Funding Use
Rein will use the $25 million for product development, agentic research and global hiring.
## Security Impact
Rein’s platform blocks harmful actions without routing data through gateways or proxies, securing agent supply chains.
## Key takeaway

Rein Security raised $25 million in Series A funding to secure AI agents against attacks, with 8x revenue growth since 2026 launch.