T-Mobile has suffered yet another data breach, this one compromising customer PINs and other sensitive information.

First spotted by Ars Technica, the Maine Attorney General posted a notification on its website. The breach impacts a small number of clients, just 836, but includes critical information that hackers could, theoretically, use to access accounts.

In a letter sent to customers, T-Mobile acknowledged the breach and said it had taken steps to address it:

Our systems recently detected that a bad actor accessed limited information from a small number of T-Mobile accounts, including your T-Mobile account PIN. Personal financial account information and call records were NOT affected. Our systems and policies enabled T-Mobile teams to identify the activity, terminate it, and implement measures to protect against it from occurring again in the future. To further protect your account, we have already proactively reset your PIN.

T-Mobile has suffered multiple data breaches in recent years, with the company’s internal systems reportedly compromised more than 100 times in in 2022 alone.