CVE-2026-117603
CVE-2026-117603
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.
Vulnerability class: TOCTOU (Time-of-Check to Time-of-Use)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 4.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N.
EPSS exploit prediction
No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.
Weakness classification (CWE)
References
- github.com/spesmilo/electrum/security/advisories/GHSA-q7m2-785w-r585 (vendor-advisory)
- github.com/spesmilo/electrum/commit/5222374046d2a92da371d46c79ce0e61e7e2a42d (patch)
- github.com/spesmilo/electrum/commit/3956bff0684f6060fbe8c823c3ee921928cdcaa5 (patch)
- www.vulncheck.com/advisories/electrum-before-4.7.2-nostr-wallet-connect-plugin-… (third-party-advisory)
Frequently asked questions
- What is CVE-2026-117603?
- CVE-2026-117603 is a medium-severity vulnerability, classified under Time-of-check Time-of-use (TOCTOU) Race Condition. CVSS score: 4.3/10. Published 2026-10-27.
- How severe is CVE-2026-117603?
- Medium severity. CVSS v3 base score is 4.3 out of 10.