The round
HiddenLayer raised $100 million in Series B funding on September 2, 2026, led by Delta-v Capital, with Ten Eleven Ventures, Morgan Stanley, M12 (Microsoft Ventures), and Booz Allen Ventures participating. Total funding is now approximately $150 million, following a $50 million Series A three years earlier.
Why now
Enterprises moved from AI experimentation to production at scale in 2026, and autonomous agents are the central risk surface that existing security tooling was not designed to handle. Autonomous agents now account for more than 1 in 8 reported AI breaches, per HiddenLayer's 2026 AI Threat Landscape Report. Prompt injection is the top entry on the OWASP Top 10 for LLM Applications 2026 and saw a 340% year-over-year increase in attacks. The timing of this round is a direct response to that acceleration.
What they are building
The Series B capital is going into agentic runtime security: prompt injection detection, identification of malicious tool calls, data exfiltration monitoring, and cascading attack chain detection for multi-agent workflows. A new product called Agent Harness Security extends the platform to AI coding agents operating in CI/CD pipelines. Autonomous coding agents that write and ship code are now the most consequential AI exposure surface for organizations adopting AI-assisted development.
The gap the market is responding to
96% of organizations call AI critical to their core operations, per the same HiddenLayer report. Nearly a third cannot confirm whether they have experienced an AI-related breach. High dependency and low visibility: this is the same pattern that defined cloud security circa 2015 and endpoint security circa 2010. The next two years will determine whether the AI security market consolidates early or stays fragmented long enough for a major incident to reset the conversation.
Context for security architects
If you are evaluating AI security tooling for agentic workloads, the capability set to benchmark against now includes runtime prompt injection detection, tool call integrity monitoring, and cross-agent chain analysis. Agent Harness Security adds coding-agent-specific coverage, which matters directly if your organization runs automated code generation in a CI/CD pipeline. HiddenLayer is not the only vendor in this space, but this round gives them the runway to build enterprise integrations aggressively.
Gigia Tsiklauri is a Security Architect and founder of Infosec.ge. Get in touch if you are evaluating AI security tooling for agentic workloads or CI/CD pipelines.