CVE-2026-70604

Electron: Custom protocol with supportFetchAPI but not corsEnabled allows cross-origin reads

Workarounds

Set corsEnabled: true on schemes that must enforce CORS, and validate the request Origin in your protocol handler before returning sensitive data.

Fixed Versions

• 42.0.0
• 41.4.0
• 40.9.3
• 39.8.10

For more information

If you have any questions or comments about this advisory, email Electron at [email protected]

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. Apps that set corsEnabled: true, or that do not load untrusted content, are not affected.

CVE-2026-70604 has a CVSS score of 7.4 (High). The vector is network-reachable, no privileges required, and user interaction required. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (42.0.0, 41.4.0, 40.9.3, 39.8.10); upgrading removes the vulnerable code path.

Kodem intelligence

Already deployed Kodem?

1. What is CVE-2026-70604? CVE-2026-70604 is a high-severity security vulnerability in electron (npm), affecting versions >= 42.0.0-alpha.1, < 42.0.0. It is fixed in 42.0.0, 41.4.0, 40.9.3, 39.8.10.
2. How severe is CVE-2026-70604? CVE-2026-70604 has a CVSS score of 7.4 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of electron are affected by CVE-2026-70604? electron (npm) versions >= 42.0.0-alpha.1, < 42.0.0 is affected.
4. Is there a fix for CVE-2026-70604? Yes. CVE-2026-70604 is fixed in 42.0.0, 41.4.0, 40.9.3, 39.8.10. Upgrade to this version or later.
5. Is CVE-2026-70604 exploitable, and should I be worried? Whether CVE-2026-70604 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2026-70604 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2026-70604?
   • Upgrade electron to 42.0.0 or later
   • Upgrade electron to 41.4.0 or later
   • Upgrade electron to 40.9.3 or later
   • Upgrade electron to 39.8.10 or later

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