Bug 2561978 (CVE-2026-117603)

Summary:	CVE-2026-117603 electrum: Electrum before 4.7.2 Nostr Wallet Connect Plugin Daily Spending Limit Bypass
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	Assignee:	Product Security <prodsec-ir-bot>
Status:	NEW ---	QA Contact:
Severity:	urgent	Docs Contact:
Priority:	urgent
Version:	unspecified	Keywords:	Security
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Hardware:	All
OS:	Linux
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Doc Text:	A flaw was found in the Nostr Wallet Connect (NWC) plugin for Electrum. Due to race conditions in budget validation and improper rounding of fractional payment units, an attacker connected to the wallet can bypass configured daily spending limits. By sending concurrent payment requests or repeatedly submitting fractional payment amounts, a malicious client can deplete wallet balances beyond authorized thresholds.	Story Points:	---
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oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:	2567154
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Description OSIDB Bzimport 2026-10-27 13:51:40 UTC

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.