CVE-2026-34778: Electron Service Worker Can Spoof ExecuteJavaScript Vulnerability

MODERATE
Advisory Identifier: GHSA-xj5x-m3f3-5x3h
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CVSS 5.9
CWE-345 CWE-290
Published
Advisory Summary

CVE-2026-34778 is a MODERATE (CVSS 5.9) service worker can spoof executejavascript vulnerability (CWE-345: Insufficient Verification of Data Authenticity) affecting Electron libraries in the npm ecosystem. The issue involves service worker can spoof executejavascript ipc replies. Remediation is available by upgrading affected packages to version 38.8.6, 39.8.1, 40.8.1, 41.0.0.

CVE-2026-34778 at a Glance

CVE Identifier CVE-2026-34778
GHSA Identifier GHSA-xj5x-m3f3-5x3h
Severity MODERATE
CVSS v3.1 Base Score 5.9
CWE Classification CWE-345: Insufficient Verification of Data Authenticity
Affected Product Electron
Package Ecosystem npm
Published Date
Last Updated

Security Impact

CVSS: 5.9

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

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

How to Fix CVE-2026-34778

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: 38.8.6 
npm install electron@38.8.6
electron fixed: 39.8.1 
npm install electron@39.8.1
electron fixed: 40.8.1 
npm install electron@40.8.1
electron fixed: 41.0.0 
npm install electron@41.0.0
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-2026-34778, 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 38.8.6), 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-345: Insufficient Verification of Data Authenticity, where the product does not sufficiently verify the origin or authenticity of data, in a way that causes it to accept invalid data. 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 service worker running in a session could spoof reply messages on the internal IPC channel used by `webContents.executeJavaScript()` and related methods, causing the main-process promise to resolve with attacker-controlled data. Apps are only affected if they have service workers registered and use the result of `webContents.executeJavaScript()` (or `webFrameMain.executeJavaScript()`) in security-sensitive decisions. ### Workarounds Do not trust the return value of `webContents.executeJavaScript()` for security decisions. Use dedicated, validated IPC channels for security-relevant communication with renderers. ### Fixed Versions * `41.0.0` * `40.8.1` * `39.8.1` * `38.8.6` ### For more information If there are any questions or comments about this advisory, please email [security@electronjs.org](mailto:security@electronjs.org)

CVE-2026-34778 Affected Electron Versions

4 component(s)
Fixed Versions:
38.8.639.8.140.8.141.0.0
Product / Package Ecosystem Affected Versions Fixed Version
electron
npm/electron
npm
< 38.8.6
38.8.6
electron
npm/electron
npm
≥ 39.0.0-alpha.1
< 39.8.1
39.8.1
electron
npm/electron
npm
≥ 40.0.0-alpha.1
< 40.8.1
40.8.1
electron
npm/electron
npm
≥ 41.0.0-alpha.1
< 41.0.0
41.0.0

References

GitHub Advisory / Wiki ADVISORY
https://github.com/electron/electron/security/advisories/GHSA-xj5x-m3f3-5x3h
NVD — CVE-2026-34778 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-34778
Electron Source Repository REPOSITORY
https://github.com/electron/electron

Frequently Asked Questions

What is CVE-2026-34778?
CVE-2026-34778 is a security vulnerability in Electron involving Service worker can spoof executeJavaScript IPC replies under CWE-345: Insufficient Verification of Data Authenticity.
Which Electron versions are affected?
Affected versions include releases prior to 38.8.6, 39.8.1, 40.8.1, 41.0.0 across affected packages: electron.
What version fixes CVE-2026-34778?
Upgrading to 38.8.6, 39.8.1, 40.8.1, 41.0.0 (or the latest patched release for your respective branch) resolves the vulnerability.
Is electron affected?
Yes, electron is affected in releases prior to 38.8.6, 39.8.1, 40.8.1, 41.0.0. Upgrade your dependency to 38.8.6, 39.8.1, 40.8.1, 41.0.0 or later.
What is the CVSS score of CVE-2026-34778?
CVE-2026-34778 has a CVSS v3.1 base score of 5.9 (MODERATE) with vector string CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:H/A:N.
What CWE is associated with CVE-2026-34778?
CVE-2026-34778 is classified under CWE-345: Insufficient Verification of Data Authenticity (The product does not sufficiently verify the origin or authenticity of data, in a way that causes it to accept invalid data.).
How can I check npm dependencies for CVE-2026-34778?
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-xj5x-m3f3-5x3h",
  "modified" : "2026-04-06T23:11:12Z",
  "published" : "2026-04-03T02:44:59Z",
  "aliases" : [ "CVE-2026-34778" ],
  "summary" : "Electron: Service worker can spoof executeJavaScript IPC replies",
  "details" : "### Impact\nA service worker running in a session could spoof reply messages on the internal IPC channel used by `webContents.executeJavaScript()` and related methods, causing the main-process promise to resolve with attacker-controlled data.\n\nApps are only affected if they have service workers registered and use the result of `webContents.executeJavaScript()` (or `webFrameMain.executeJavaScript()`) in security-sensitive decisions.\n\n### Workarounds\nDo not trust the return value of `webContents.executeJavaScript()` for security decisions. Use dedicated, validated IPC channels for security-relevant communication with renderers.\n\n### Fixed Versions\n* `41.0.0`\n* `40.8.1`\n* `39.8.1`\n* `38.8.6`\n\n### For more information\nIf there are any questions or comments about this advisory, please email [security@electronjs.org](mailto:security@electronjs.org)",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:H/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "electron"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "38.8.6"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "npm",
      "name" : "electron"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "39.0.0-alpha.1"
      }, {
        "fixed" : "39.8.1"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "npm",
      "name" : "electron"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "40.0.0-alpha.1"
      }, {
        "fixed" : "40.8.1"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "npm",
      "name" : "electron"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "41.0.0-alpha.1"
      }, {
        "fixed" : "41.0.0"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/electron/electron/security/advisories/GHSA-xj5x-m3f3-5x3h"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-34778"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/electron/electron"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-290", "CWE-345" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-04-03T02:44:59Z",
    "nvd_published_at" : "2026-04-04T00:16:19Z"
  }
}