Did you happen to do anything online that has to do with applying for credit?
No. Equifax is one of the reporting agencies though. If you’ve ever used credit before (and who hasn’t even if it’s just a mortgage) you’re in their files.
I am looking at the reported cause though. A website security issue.
This would be something, some transaction, that causes the website to want to look at your credit. It could be applying for a credit card. It could be signing up for some transaction where the extender of the transaction wants to know how well it can trust you. Renting a car could fall into that category.