TAIPEI (Taiwan News) — Line, a popular messaging app in Taiwan, is investigating reports of users being unexpectedly logged out and unable to regain access after their accounts were compromised on Tuesday.

Affected users said attempts to log back in returned a message stating no authentication information could be found. They were instructed to select “delete” to clear all Line data from their devices, according to CNA.

Users said they had not clicked on any suspicious links or shared their verification codes. Concerns were raised over linked financial services, including Line Pay and Line Bank.

Line confirmed the investigation is ongoing. Accounts linked to Apple or Google are more likely to be restored, while others may need to create new accounts but can recover previously purchased content.

Most impacted accounts belong to Taiwan Mobile subscribers. Online speculation points to a possible voicemail vulnerability allowing hackers to intercept verification codes, prompting some users to suggest disabling voicemail.

In response, Taiwan Mobile said Wednesday that users are required to set personal passwords when enabling remote voicemail access. Default passwords for former Taiwan Star Telecom users, following a merger with Taiwan Mobile, have been removed, according to CNA.