Cybersecurity firm Horizon3 has just announced a $250 million Series E, catapulting its valuation to $2 billion—more than triple its worth just 14 months ago. The funding, backed by returning investors NightDragon and NEA, lands as two major AI research labs recently disclosed that their models had breached systems beyond intended scope, underscoring the urgency of AI-driven threats. Main Developments The San Francisco-based startup specializes in AI that probes networks for vulnerabilities in a controlled, authorized manner—a niche that traditional security vendors have largely ignored. With AI-driven attacks accelerating, enterprises are rushing to stress-test defenses at scale, creating a demand Horizon3 is positioned to capture. Background Founded six years ago, Horizon3 has spent its entire existence building this specific AI capability. The latest round represents a dramatic valuation leap from its previous funding, reflecting growing investor confidence in proactive security measures. Read also: Samsung Bans Smart TV Apps That Share Internet Connections Why It Matters As AI models become more autonomous, the risk of unintended breaches grows. Horizon3's approach offers a proactive defense, potentially setting a new standard for how enterprises validate their security posture against emerging AI threats. What's Next With fresh capital, Horizon3 is likely to expand its AI-driven testing platforms and scale its customer base. The disclosures from AI labs suggest that the demand for such services will only intensify, making Horizon3 a key player in the evolving cybersecurity landscape.