Electrum before 4.7.2 Nostr Wallet Connect Plugin Daily Spending Limit Bypass

Summary

Electrum before 4.7.2 contains a spending limit bypass vulnerability in the Nostr Wallet Connect plugin that allows malicious NWC clients to exceed daily_limit_sat by exploiting non-atomic budget checks and millisatoshi truncation. Attackers can send concurrent pay_invoice requests that pass budget_allows_spend() before add_to_budget() runs, or repeatedly pay msat amounts that are floored to whole satoshis, to drain funds beyond the limit.

Affected versions

• spesmilo electrum

  fixed in 4.7.2

References 4