A data breach at Stockholm Public Library has compromised the information of thousands of users, prompting email notifications to those affected. Investigative journalist Linus Larsson from *Dagens Nyheter* attributes the security lapse to the use of easily guessable PIN codes by library patrons. The vulnerability allowed unauthorized access to user accounts and subsequent data leakage. The extent of the compromised data remains under investigation, but officials confirm personal information was exposed. Larsson addresses five key questions regarding the incident, shedding light on the cause and potential impact. The library is urging users to update their PINs to stronger, more secure combinations to prevent further breaches. This incident highlights the importance of robust password security practices for online accounts.