T-Mobile has disclosed a data breach that exposed customer private network information (CPNI), which includes phone numbers and call history.

T-Mobile started messaging consumers about a “security issue” that revealed the details of their accounts yesterday.

T-Mobile claims that recently, their systems had “malicious, unauthorised access” uncovered by their security staff. T-Mobile hired a cybersecurity company to conduct an investigation, and the results showed that threat actors had gotten access to CPNI, or customer-generated network information, used for telecommunications.

Phone numbers, call history, and the number of lines on an account are among the data compromised in this attack.

“The Federal Communications Commission (FCC) regulations’ definition of customer proprietary network information (CPNI) was accessed. The CPNI that was accessed may have included your phone number, the number of lines you have subscribed to, and, in certain circumstances, call-related data gathered as part of your cellular service’s routine operation “T-Mobile claimed in a notification of a data breach.

According to T-Mobile, the compromised data did not include the names, addresses, email addresses, financial information, credit card information, social security numbers, tax IDs, passwords, or PINs of account users.

T-Mobile claimed that this hack only affected a “small number of consumers (less than 0.2%)” in a statement to BleepingComputer. There are roughly 200,000 persons who have been impacted by this breach out of T-estimated Mobile’s 100 million subscribers.

“Less than 0.2% of our clients are now receiving notifications that some account information may have been improperly accessed. Names connected to the account, financial information, credit card details, social security numbers, passwords, PINs, and physical or email addresses were NOT among the data obtained. Phone numbers, the number of lines a user subscribes to, and, in a few rare situations, call-related data gathered as part of routine operation and service, were among the data that may have been accessed “Tells BleepingComputer, T-Mobile.

Anyone who has received a text alert about this incident should be on the watch for any suspicious texts that seem to be from T-Mobile and ask for information or contain links to websites that are not owned by T-Mobile.

Threat actors frequently employ information they have obtained from other targeted phishing and smishing efforts in an effort to get sensitive data such login names and passwords.

Prior data breaches at T-Mobile occurred in 2018, 2019 for prepaid users, and in March 2020, which exposed personal and financial information.