# CVE-2026-117603: Electrum before 4.7.2 Nostr Wallet Connect Plugin Daily Spending Limit Bypass


- **Severity:** Critical 9.3 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Fix available:** Yes
- **Published:** 27 Oct 2026
- **Updated:** 27 Oct 2026
- **Also known as:** DEBIAN-CVE-2026-117603, GHSA-98mp-7r7x-725c, GHSA-q7m2-785w-r585

## What is CVE-2026-117603?

CVE-2026-117603 is a critical vulnerability in spesmilo electrum, published on 27 Oct 2026. 

### Official description

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.

Weakness: CWE-367 (Time-of-check Time-of-use (TOCTOU) Race Condition)

## Which versions are affected by CVE-2026-117603?


## How do I fix CVE-2026-117603?

Upgrade to a fixed version.

## Is CVE-2026-117603 being exploited?

There is no known exploitation of CVE-2026-117603 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-117603 and fix it if it is affected.

What it is: CVE-2026-117603 is a critical vulnerability in spesmilo electrum, published on 27 Oct 2026. 
Exploitation: There is no known exploitation of CVE-2026-117603 in the wild and no public exploit code.

Affected product: spesmilo electrum. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-117603/ (Markdown: https://insights.sbomify.com/CVE-2026-117603/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-117603
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-117603
- OSV: https://osv.dev/vulnerability/CVE-2026-117603

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-117603/
Summaries are generated and may contain mistakes; the official description above is the record.