This is a good read,
Why the Equifax breach is very possibly the worst leak of personal info ever | Ars Technica
Basically they gave their security to amateurs and you shouldn't trust anything they do.
I can pretty much guarantee you that someone somewhere is trying to abuse their "checking" site to scrape the data entered on it and I don't trust them to be good enough not to do something stupid like dump data into a log or unprotected cache while the server is slammed with entries.