As reports niebezpiecznik.pl on the government website biznes.gov.pl anyone could have access to classified information from entrepreneurs through a simple trick. Namely - by going to the My company tab, then clicking View details, you can see classified data about your company, mainly, certificates. The trick was that by properly editing the URL, you could enter the ID of another entrepreneur, and thus have access to his classified data.

"https://konto.biznes.gov.pl/pl/moje-konto/moja-firma/(modal:podglad-wpisu/[IDENTYFIKATOR])"

The data that can be found there is PESEL or date of birth, and not everyone would like to disclose their PESEL for obvious reasons.

Source and more details: niebezpiecznik.pl