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CriticalVulnerabilityCVE-2026-117603updated 27 Oct 2026, 14:19 UTC

Electrum wallet spending limit can be bypassed via Nostr Wallet Connect

A connected app can spend more of your Bitcoin than the daily limit you set. It does this by sending several payment requests at the same moment, or by using tiny fractional amounts that get rounded down, so the limit check does not catch t

Fixed in Electrum 4.7.2 or later.Official source
SeverityCriticalCVSS 9.3 of 10
Being exploited?UnclearNo reports either way yet
Fix available?YesElectrum 4.7.2 or later. · since 27 Oct 2026
How sure is this?Official sourceBacked by an official source

How the attack works simplified

  1. 1Malicious NWC clientConnected app controlled by attacker
  2. 2Concurrent requestsSeveral pay_invoice calls sent at once
  3. 3Budget check passesCheck runs before the budget is updated
  4. 4Msat roundingFractional amounts are floored to whole sats
  5. 5Funds drainedSpending exceeds the daily limit
  6. ResultWallet spends beyond the daily limit

What happened

In Electrum before 4.7.2, the Nostr Wallet Connect plugin performs non-atomic budget checks (the spend check and budget update are not done together, allowing concurrent pay_invoice requests to pass) and floors millisatoshi amounts to whole satoshis, letting malicious NWC clients exceed daily_limit_sat.

Why it is dangerous: A malicious or compromised NWC client can drain funds from the wallet beyond the configured daily spending limit, which is the safeguard meant to limit losses.

Are you affected?

You are affected if you run Electrum older than 4.7.2 with the Nostr Wallet Connect plugin enabled and have connected a third-party NWC client.

Electrum versions before 4.7.2 with the Nostr Wallet Connect plugin.

What to do

  1. Update Electrum to version 4.7.2 or later
  2. Disconnect any NWC clients you do not fully trust until the update is installed
  3. Lower your daily spending limit or disable the NWC plugin if you cannot update right away

Timeline

  1. 27 Oct 2026, 14:16 UTC
    Publicly disclosed
  2. 27 Oct 2026, 14:16 UTC
    Reported by NVD · NVD
  3. 27 Oct 2026, 14:19 UTC
    Picked up by Zero Radar

Sources 1 report, oldest first

Official vendor, government CERT or advisory database

Technical details

ID
CVE-2026-117603
CVSS
9.3 / 10
EPSS
0.2% chance of exploitation within 30 days
Disclosed
27 Oct 2026, 14:16 UTC
On Zero Radar
27 Oct 2026, 14:19 UTC (3 min after disclosure)
Last change
27 Oct 2026, 14:19 UTC

The plain-language parts and the attack diagram were written by an AI model (anthropic/claude-haiku-5.5) from the sources above. Facts like versions, exploitation and dates come from the sources themselves. How Zero Radar works

Electrum wallet spending limit can be bypassed via Nostr Wallet Connect · Zero Radar