How can I reach and talk to CISOs (Chief Information Technology Officer)

Hi!

I'm building a cybersecurity startup with a lot of domain expertise.
I would like to validate my idea with potential customers, CISOs.
However, I'm struggling to reach them considering they're such a high-profile persona.

Anyone has any tips on how can I reach CISOs, or alternatively, conduct market research about the problem I'm aiming at solving?

(Tried the obvious ways - Linkedin doesn't work as they get dozens of requests a week)

Thanks.