Seoul’s Ttareungyi public bike service under probe for data leak of 4.5 million users

Ttareungyi bicycles are parked at a rental station in Seoul, Nov. 12, 2025. Newsis

City authorities in Seoul are investigating a massive data leak affecting millions of users of its public bicycle service Ttareungyi after reports surfaced that personal information may have been exposed online.

The Seoul Facilities Corporation (SFC), a public entity that operates Ttareungyi, said Friday it was informed by the Seoul Metropolitan Police Agency’s cyber investigation unit about the suspected leak of the personal data of some 4.5 million users.

Ttareungyi, a key part of Seoul’s green transportation network launched in 2015, had more than 5 million cumulative users as of the end of 2025.

According to the SFC, the leaked data appears to include user IDs and mobile phone numbers. Officials said no evidence indicates that more sensitive personal information, such as names or resident registration numbers, was collected or leaked. Police are working to identify the scope of the breach and how it occurred.

In response, the SFC reported the incident to the Personal Information Protection Commission and the Korea Internet & Security Agency. The SFC also launched an emergency response team in cooperation with the Seoul Metropolitan Government to assess the damage and to enhance system security.

“We plan to fully cooperate with the police investigation and promptly take any necessary follow-up measures based on the investigation’s findings,” an SFC official said in a statement.