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.