Electrum Warns of Exploited Wallet Flaw in Versions Before 4.8.3

Electrum warned that attackers are exploiting a vulnerability in Bitcoin (BTC) wallet releases before 4.8.3, where a fee increase can prompt the software to sign a payment redirecting funds to an attacker. The attack begins when a user tries to raise a transaction fee through Replace-by-Fee (RBF). A malicious server can intercept the broadcast transaction, then cause the wallet history to show a counterfeit transaction sending BTC to an attacker-controlled address. Electrum may sign the substituted transaction as part of the fee increase.