Electrum Wallet Attack Hid Bitcoin Theft Behind a Fee Increase

A malicious bitcoin wallet server could quietly swap a legitimate payment for a thief’s transaction, then wait for its owner to approve the theft. Electrum’s latest security patch closes that loophole after attackers exploited the flaw and stole funds. Electrum released version 4.8.3 on Saturday, warning users to upgrade immediately after developers discovered that malicious servers were exploiting a high-severity vulnerability affecting every earlier version. The flaw, documented in GitHub advisory GHSA-6jp4-8v48-cc5v, exploited how the lightweight Bitcoin wallet handles unconfirmed transactions. Electrum relies on external servers for transaction histories, fee estimates, and broadcasting payments. While it independently checks confirmed transactions, older versions accepted certain unconfirmed transactions without verifying their signatures. Attackers turned that distinction into a trap.

First reported by Bitcoin.com News. This page is a short excerpt; the full text is theirs.