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High, CVSS 7.4

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

CVE-2026-70604GHSA-v3j7-r9gq-3gjw

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (electron 42.0.0, 41.4.0, 40.9.3, 39.8.10), redeploy, then verify what is actually installed.

This page has no inventory attached, so it cannot say whether you are affected. A vendor fix is not proof that your deployment is fixed.

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Affected packages

  • npm electron

    Affected
    >= 42.0.0-alpha.1, < 42.0.0>= 41.0.0-alpha.1, < 41.4.0>= 40.0.0-alpha.1, < 40.9.3< 39.8.10
    Fixed in
    39.8.10, 40.9.3, 42.0.0, 41.4.0

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS
7.4 · CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:N/A:N
EPSS
  • CVE-2026-70604: 0.35% estimated exploitation activity in the next 30 days; percentile 29.22 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.
Source description

As published by the source; long descriptions are shortened.

Impact 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. 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 security@electronjs.org

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 1 · created ·

    Published from ghsa record GHSA-v3j7-r9gq-3gjw

Agent brief

Preview the exact text before you copy it. Commands are read-only suggestions; review them before running anything.

# Patch Next advisory brief: CVE-2026-70604

Advisory: Electron: Custom protocol with supportFetchAPI but not corsEnabled allows cross-origin reads
IDs: CVE-2026-70604, GHSA-v3j7-r9gq-3gjw
Record: https://patchnext.com/advisories/cve-2026-70604 (revision 1, source checked 26 Oct 2026, 13:00 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.4)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: electron 42.0.0, 41.4.0, 40.9.3, 39.8.10. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm electron: affected >= 42.0.0-alpha.1, < 42.0.0; >= 41.0.0-alpha.1, < 41.4.0; >= 40.0.0-alpha.1, < 40.9.3; < 39.8.10; fixed in 39.8.10, 40.9.3, 42.0.0, 41.4.0

## Suggested inspection (read-only)
- `npm ls electron --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on electron.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-v3j7-r9gq-3gjw (GitHub-reviewed advisory GHSA-v3j7-r9gq-3gjw lists affected ranges: npm electron >=42.0.0-alpha.1 =41.0.0-alpha.1 =40.0.0-alpha.1 =0 <39.8.10)

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