Upbit and Bithumb announced through a notice that they have decided to issue a caution regarding Polkadot (DOT). The exchanges stated, "On April 13, 2026, circumstances indicating a security issue with Polkadot (DOT) were confirmed. Due to this, there is concern about increased price volatility for Polkadot (DOT), and we ask investors to exercise extreme caution when investing in Polkadot (DOT)."