Electron: Service worker can spoof executeJavaScript IPC replies

### 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)