Millions of South Koreans rely on KakaoTalk — the country’s most popular and ubiquitous messaging app — for everything from chatting with friends and family to accessing essential services. However, new research has exposed longstanding business practices that could heighten the app’s vulnerabilities.

These reported vulnerabilities potentially allow attackers — as well as Kakao — to access users’ supposedly encrypted chats, reawakening past concerns about the privacy of KakaoTalk users’ personal communications.