Electrum: Malicious server can replace a just-broadcast tx and try to trick user into RBF-ing it

影響: pip:electrum < 4.8.3 → 4.8.3

The main Electrum server the client connects to is trusted with mempool ("unconfirmed") transactions. This is documented [design](https://electrum.readthedocs.io/en/latest/faq.html#does-electrum-trust-servers). [0] However now someone figured out a way to practically exploit it: - when the client broadcasts a new tx1, a malicious server can swallow it, - and update the client's history with a conflicting (invalid) tx2 that replaces the outputs with the attacker's output address. - Tx2 has inval…

Read on GitHub Advisory Database

On 10/29/2026, 06:23 AM, GitHub Advisory Database published "Electrum: Malicious server can replace a just-broadcast tx and try to trick user into RBF-ing it" (type: Advisory). Severity is "Critical" (critical). Related technologies: Python. CVE: CVE-2026-117601.