Electrum 4.8.3 fixes flaw that let malicious servers redirect Bitcoin payments

• —A malicious server dropped the user's real transaction and injected a conflicting zero-fee one paying the attacker
• —Electrum did not verify signatures on unconfirmed transactions supplied by servers
• —The attacker can even match the last four characters of the intended address
• —All versions before 4.8.3 are affected; incoming transactions from external senders still go unverified