Nebulock raises $25M Series A as AI-powered security firms pull in funding

Contextual security startup Nebulock has raised a $25 million Series A led by FirstMark, founder and CEO Damien Lewke told Axios exclusively. The company helps security teams proactively find and remediate threats across a company's security stack, positioning itself in a market that is drawing heavy investment as AI adoption accelerates.

The round closed in June 2026, adding to a $10 million seed round Nebulock closed less than 18 months earlier. The company plans to use the new capital to expand its engineering team and double down on product development for its contextual threat detection platform.

Coval and 360 add to the funding wave

Coval raised $28 million in a Series A round to stress-test AI voice agents before they reach real callers. The company's founder previously built safety checks for Waymo's self-driving cars and argues that voice AI needs the same rigorous testing. An AI voice agent can sound flawless in a demo and fall apart on a real call, the company says. Coval's platform simulates thousands of call scenarios to catch failures early.

In China, cybersecurity firm 360 unveiled two products it calls "China's version of Mythos" and Yitianzhen, aiming to automate cyber defense. The company stated that China "cannot afford to wait" as Mythos continues to find more flaws. The tools are designed to automatically detect and patch vulnerabilities without human intervention, reflecting a growing national urgency around AI-era security.

• Nebulock: $25M Series A from FirstMark, contextual threat detection across security stack.
• Coval: $28M Series A to test AI voice agents for safety before deployment.
• 360 (China): Launched "China's version of Mythos" and Yitianzhen for automated cyber defense.

Investor appetite signals market shift

FirstMark's lead in the Nebulock round signals venture appetite for security tools that layer context onto alerts rather than just adding more noise. Contextual security correlates signals from multiple tools to reduce false positives and speed up remediation. The approach matches a pattern seen across recent funding rounds where investors favor platforms that consolidate and interpret data over point products.

Coval's $28 million raise for voice agent testing points to an emerging niche. As enterprises deploy voice bots in customer service, healthcare, and finance, the risk of a bot hallucinating or mishandling sensitive data grows. Testing those agents at scale is becoming a requirement, not a luxury.

What comes next is likely more consolidation. Nebulock will compete with established SIEM and SOAR vendors while Coval faces a nascent but fast-growing category. In China, 360's automated defense tools may see rapid adoption given government mandates on cybersecurity. All three companies are betting that AI-driven threats require AI-driven defenses, a thesis investors are funding at record pace.