CVE-2026-34778
Electron: Service worker can spoof executeJavaScript IPC replies
Description
### 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)
How to fix CVE-2026-34778
To remediate CVE-2026-34778, upgrade the affected package to a fixed version below.
- —upgrade to 38.8.6 or later
Is CVE-2026-34778 being exploited?
Low — EPSS is 0.0%, meaning exploitation activity has not been observed at scale.
Affected packages (1)
- from 0, < 38.8.6
CVSS scores
| Source | Version | Severity | Vector |
|---|---|---|---|
| osv | CVSS 3.1 | MEDIUM5.9 | CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:H/A:N |