# Electrum Users Urged to Update After Fee-Bump Bitcoin Theft

By Simon Yoon

Canonical URL: https://www.tokenpost.com/news/technology/40451
Published: 2026-10-25T09:07:48.000Z
Updated: 2026-10-25T09:07:48.000Z
Section: Technology

> The flaw affected versions earlier than 4.8.3. Electrum received two user reports, including one involving lost funds.

Electrum urged users to update to version 4.8.3 after disclosing a high-risk flaw that let malicious servers redirect Bitcoin (BTC) payments when users tried to raise transaction fees.

The flaw affected all versions earlier than 4.8.3. A malicious server could hide a newly broadcast payment and replace it in the wallet’s history with an invalid transaction to an attacker’s address. If a user then raised the fee through Replace-by-Fee, the wallet could sign the substituted transaction.

Electrum received two private user reports, dated Oct. 11 and Oct. 18. Both described attacker addresses that shared the last four characters of the intended recipient’s address. The Oct. 18 report involved lost funds after a fee increase; the amount was not disclosed.

The fix was tagged Friday, Oct. 23, and binaries were released Saturday, Oct. 24. Electrum recommends downloading only from electrum.org and verifying GPG signatures. Its design relies on servers to report unconfirmed transactions; users connected to servers they trust, including servers they operate themselves, were not affected by this attack.