Electron is a framework for writing cross-platform desktop applications using JavaScript, HTML and CSS. Prior to 39.8.5, 40.8.5, 41.1.0, and 42.0.0-alpha.5, when a renderer calls window.open() with a target name, Electron did not correctly scope the named-window lookup to the opener's browsing context group. A renderer could navigate an existing child window that was opened by a different, unrelated renderer if both used the same target name. If that existing child was created with more permissive webPreferences (via setWindowOpenHandler's overrideBrowserWindowOptions), content loaded by the second renderer inherits those permissions. Apps are only affected if they open multiple top-level windows with differing trust levels and use setWindowOpenHandler to grant child windows elevated webPreferences such as a privileged preload script. Apps that do not elevate child window privileges, or that use a single top-level window, are not affected. Apps that additionally grant nodeIntegration: true or sandbox: false to child windows (contrary to the security recommendations) may be exposed to arbitrary code execution. This vulnerability is fixed in 39.8.5, 40.8.5, 41.1.0, and 42.0.0-alpha.5.

Affected: npm: electron

### Impact When a renderer calls `window.open()` with a target name, Electron did not correctly scope the named-window lookup to the opener's browsing context group. A renderer could navigate an existing child window that was opened by a different, unrelated renderer if both used the same target name. If that existing child was created with more permissive `webPreferences` (via `setWindowOpenHandler`'s `overrideBrowserWindowOptions`), content loaded by the second renderer inherits those permissions.

Apps are only affected if they open multiple top-level windows with differing trust levels **and** use `setWindowOpenHandler` to grant child windows elevated `webPreferences` such as a privileged preload script. Apps that do not elevate child window privileges, or that use a single top-level window, are not affected.

Apps that additionally grant `nodeIntegration: true` or `sandbox: false` to child windows (contrary to the [security recommendations](https://www.electronjs.org/docs/latest/tutorial/security)) may be exposed to arbitrary code execution.

### Workarounds Deny `window.open()` in renderers that load untrusted content by returning `{ action: 'deny' }` from `setWindowOpenHandler`. Avoid granting child windows more permissive `webPreferences` than their opener.

### Fixed Versions * `42.0.0-alpha.5` * `41.1.0` * `40.8.5` * `39.8.5`

### For more information If you have any questions or comments about this advisory, email us at [security@electronjs.org](mailto:security@el…