LINE Messaging Bugs Open Asian Users to Cyber Espionage

Researchers from Aarhus University found critical design flaws in LINE's custom E2EE protocol (Letter Sealing v2) that permit message replay, plaintext leakage (stickers and URL previews), and impersonation by any chat participant if a malicious LINE server or MiTM position is achieved; the issues could affect millions of users exchanging billions of messages, and LINE has acknowledged the findings but indicated limited plans for protocol redesign or fixes.