CVE-2026-70604: Electron Custom Protocol With SupportFetchAPI But Vulnerability

HIGH
Advisory Identifier: GHSA-v3j7-r9gq-3gjw
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CVSS 7.4
CWE-942
Published
Advisory Summary

CVE-2026-70604 is a HIGH (CVSS 7.4) custom protocol with supportfetchapi but vulnerability (CWE-942: Permissive Cross-domain Security Policy with Untrusted Domains) affecting Electron libraries in the npm ecosystem. The issue involves custom protocol with supportfetchapi but not corsenabled allows cross-origin reads. Remediation is available by upgrading affected packages to version 42.0.0, 41.4.0, 40.9.3, 39.8.10.

CVE-2026-70604 at a Glance

CVE Identifier CVE-2026-70604
GHSA Identifier GHSA-v3j7-r9gq-3gjw
Severity HIGH
CVSS v3.1 Base Score 7.4
CWE Classification CWE-942: Permissive Cross-domain Security Policy with Untrusted Domains
Affected Product Electron
Package Ecosystem npm
Published Date
Last Updated

Security Impact

CVSS: 7.4

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:N/A:N).

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required None (PR:N)
User Interaction Required (UI:R)
Scope Changed (S:C)
Confidentiality High (C:H)
Integrity None (I:N)
Availability None (A:N)

How to Fix CVE-2026-70604

To remediate this vulnerability, upgrade all affected Electron dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

electron fixed: 42.0.0 
npm install electron@42.0.0
electron fixed: 41.4.0 
npm install electron@41.4.0
electron fixed: 40.9.3 
npm install electron@40.9.3
electron fixed: 39.8.10 
npm install electron@39.8.10
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

npm ls electron

How to Check if You Are Affected

To determine whether your Node.js application is affected by CVE-2026-70604, inspect your project dependencies using npm:

npm ls electron

Analyze the terminal output to locate any version of Electron in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 42.0.0), your application is affected.

Note: The npm ls electron command inspects dependencies declared in your package.json and lockfile; it does not perform automated runtime dynamic scanning.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-942: Permissive Cross-domain Security Policy with Untrusted Domains, where the product uses a web-client protection mechanism such as a content security policy (csp) or cross-domain policy file, but the policy includes untrusted domains with which the web client is allowed to communicate. In Electron, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

### 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](mailto:security@electronjs.org)

CVE-2026-70604 Affected Electron Versions

4 component(s)
Fixed Versions:
42.0.041.4.040.9.339.8.10
Product / Package Ecosystem Affected Versions Fixed Version
electron
npm/electron
npm
≥ 42.0.0-alpha.1
< 42.0.0
42.0.0
electron
npm/electron
npm
≥ 41.0.0-alpha.1
< 41.4.0
41.4.0
electron
npm/electron
npm
≥ 40.0.0-alpha.1
< 40.9.3
40.9.3
electron
npm/electron
npm
< 39.8.10
39.8.10

References

GitHub Advisory / Wiki ADVISORY
https://github.com/electron/electron/security/advisories/GHSA-v3j7-r9gq-3gjw
Electron Source Repository REPOSITORY
https://github.com/electron/electron

Frequently Asked Questions

What is CVE-2026-70604?
CVE-2026-70604 is a security vulnerability in Electron involving Custom protocol with supportFetchAPI but not corsEnabled allows cross-origin reads under CWE-942: Permissive Cross-domain Security Policy with Untrusted Domains.
Which Electron versions are affected?
Affected versions include releases prior to 42.0.0, 41.4.0, 40.9.3, 39.8.10 across affected packages: electron.
What version fixes CVE-2026-70604?
Upgrading to 42.0.0, 41.4.0, 40.9.3, 39.8.10 (or the latest patched release for your respective branch) resolves the vulnerability.
Is electron affected?
Yes, electron is affected in releases prior to 42.0.0, 41.4.0, 40.9.3, 39.8.10. Upgrade your dependency to 42.0.0, 41.4.0, 40.9.3, 39.8.10 or later.
What is the CVSS score of CVE-2026-70604?
CVE-2026-70604 has a CVSS v3.1 base score of 7.4 (HIGH) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:N/A:N.
What CWE is associated with CVE-2026-70604?
CVE-2026-70604 is classified under CWE-942: Permissive Cross-domain Security Policy with Untrusted Domains (The product uses a web-client protection mechanism such as a Content Security Policy (CSP) or cross-domain policy file, but the policy includes untrusted domains with which the web client is allowed to communicate.).
How can I check npm dependencies for CVE-2026-70604?
Run the dependency tree command: 'npm ls electron'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-v3j7-r9gq-3gjw",
  "modified" : "2026-08-05T15:59:45Z",
  "published" : "2026-08-05T15:59:45Z",
  "aliases" : [ "CVE-2026-70604" ],
  "summary" : "Electron: Custom protocol with supportFetchAPI but not corsEnabled allows cross-origin reads",
  "details" : "### Impact\nA 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.\n\nApps 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.\n\n### Workarounds\nSet `corsEnabled: true` on schemes that must enforce CORS, and validate the request `Origin` in your protocol handler before returning sensitive data.\n\n### Fixed Versions\n* `42.0.0`\n* `41.4.0`\n* `40.9.3`\n* `39.8.10`\n\n### For more information\nIf you have any questions or comments about this advisory, email Electron at [security@electronjs.org](mailto:security@electronjs.org)",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:N/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "electron"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "42.0.0-alpha.1"
      }, {
        "fixed" : "42.0.0"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "npm",
      "name" : "electron"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "41.0.0-alpha.1"
      }, {
        "fixed" : "41.4.0"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "npm",
      "name" : "electron"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "40.0.0-alpha.1"
      }, {
        "fixed" : "40.9.3"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "npm",
      "name" : "electron"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "39.8.10"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/electron/electron/security/advisories/GHSA-v3j7-r9gq-3gjw"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/electron/electron"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-942" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-08-05T15:59:45Z",
    "nvd_published_at" : null
  }
}