hack attempts after payment

I have set up three websites using cb subs. After probably 100 or so customers with no issues, my last sign up says there were 8 hack attempts on her paypal account after signing up, which means my website is being blamed for the problem.

Maybe I'm not understanding what the plugin does completely, but I thought the payment was mostly in the hands of paypal. Are there security issues that I am ignorant of and that I should be paying attention to when using cbsubs?

Seems to be some error logs, even though the sub and payment went through. Not sure if those identify a security issue.

There is no chance that the hack attempts on her customer Paypal account would be due to CBSubs. All Paypal sensitive data stays on the Paypal website, that's the main reason of using a payment processor.

Wondering how your customer could count hack attempts on her Paypal account. Paypal does not communicate such internal statistics. It could be even a phishing attempt email that she got from a hacker which claims that. Who knows.

Regarding your error log, it could be a silent notice which is unrelated to CBSubs. But hard to say without seeing details of one of those notices. You can click on each and see full details. The path of the files in the call stack usually helps you finding the "culprit" part.