Sure, but is vigilantism for the public good?

Close, but no.

>A white hat (or a white hat hacker) is an ethical security hacker.[1] Ethical hacking is a term meant to imply a broader category than just penetration testing.[2][3] Under the owner's consent, white hat hackers aim to identify any vulnerabilities the current system has. [...] There is a third kind of hacker known as a grey hat who hacks with good intentions but at times without permission.[6]

https://en.wikipedia.org/wiki/White_hat_(computer_security)

traditionally, white hat means working with companies to help identify weaknesses in their systems, and getting inside with their consent.