Electron is a framework for writing cross-platform desktop applications using JavaScript, HTML and CSS. Prior to 41.10.4, 42.5.2, and 43.0.0, popups opened from a sandboxed iframe through Electron's OpenURLFromTab navigation path, including links using target="_blank" or a middle-click, did not receive the inherited HTML sandbox restrictions. An untrusted iframe using the allow-scripts allow-popups configuration could therefore open a popup with the embedding application's full origin, exposing that origin's cookies, storage, and same-origin scripting capabilities. Applications that do not embed untrusted content in sandboxed iframes are not affected. This issue is fixed in versions 41.10.4, 42.5.2, and 43.0.0.

Affected: npm: electron

### Impact

Popups opened from a sandboxed iframe through a link (for example `target="_blank"` or a middle-click) did not inherit the iframe's HTML `sandbox` restrictions. Content that was meant to run sandboxed could open a popup with the embedding app's full origin, gaining access to that origin's cookies, storage, and same-origin scripting.

Apps are only affected if they embed untrusted content in iframes sandboxed with `allow-scripts allow-popups`. Apps that do not embed untrusted content in sandboxed iframes are not affected.

### Workarounds

Use `setWindowOpenHandler` on the parent `WebContents` to deny or constrain popups opened from sandboxed frames, or do not apply `allow-popups` to sandboxed iframes that render untrusted content.

### Fixed Versions

* `43.0.0` * `42.5.2` * `41.10.4`

### For more information

If you have any questions or comments about this advisory, email us at [security@electronjs.org](mailto:security@electronjs.org)