A security vulnerability in the Electron framework allows sandboxed iframes without the allow-popups keyword to bypass popup restrictions and open new windows or trigger setWindowOpenHandler without user interaction. The flaw exists because new-window navigations taking the OpenURL path did not properly enforce iframe sandbox popup restrictions. Applications embedding untrusted content in sandboxed iframes that rely on the absence of allow-popups to prevent window creation are affected. Apps that explicitly deny window creation in setWindowOpenHandler or do not embed untrusted content in sandboxed iframes are not impacted. The vulnerability affects Electron versions prior to 39.8.10, 41.10.3, and 42.0.1. Fixes have been released in versions 39.8.10, 41.10.3, and 42.0.1. Multiple commits and pull requests on GitHub address the issue across the affected version branches.