Electrum wallet security flaw is fixed after a user loses money in fee attack

Electrum released version 4.8.3 on October 24, 2026 , to fix an Electrum wallet security flaw that lets malicious servers trick users into signing payments to attackers when increasing transaction fees. Developers received two user reports, including one involving lost money, and urged everyone to upgrade. Key takeaways Electrum versions earlier than 4.8.3 are vulnerable. A manual fee increase can authorize an attacker’s substituted payment. The patch validates signatures before accepting affected unconfirmed transactions. How the Electrum wallet security flaw works A malicious server can hide a user’s original payment and replace it in the wallet’s history with a conflicting transaction pointing to an attacker-controlled address . Electrum ’s security advisory says some servers are already conducting the attack. The wallet uses servers to retrieve transaction history and broadcast payments.

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