The data of tens of thousands of employees and students of Inholland University of Applied Sciences are offered for sale online,
These would include e-mail addresses, home addresses, telephone numbers and encrypted passwords.
The school was hacked last month, but it is still unclear how the hackers got access.
It concerns a maximum of 56,000 persons, of whom at least the e-mail address has been leaked.
Some students and employees have also had their address, telephone number and encrypted password stolen.
An encrypted password cannot be read by everyone immediately.
However, these passwords can in some cases be cracked with specialized software.
It is not clear how much the criminals want for the data.
The website page where the data was offered for sale seems to have been taken offline.
The university of applied sciences has now emailed students and employees about the hacking attack.
Those affected are advised to be vigilant about phishing emails.
With the collected data, criminals can pretend to be, for example, a bank employee and try to gain the trust of an Inholland student or employee.
Lately there have been multiple cyber attacks on schools.
For example, a secondary school in Gelderland was hit last week.
A week earlier, the Amsterdam University of Applied Sciences (HvA) and the University of Amsterdam (UvA) were on the hook.
See also: Dutch Data Protection Authority sees more data theft and fewer leaks in 2020