Some window options supplied by web content in the window.open() features string were applied to the new BrowserWindow without an allowlist. Untrusted content could set window options it should not control, including options that cause the main process to access attacker-chosen file or network paths.

Apps are only affected if untrusted content can call window.open() and the app does not override child window options via setWindowOpenHandler. Apps that deny window.open() for untrusted content, or set overrideBrowserWindowOptions explicitly, are not affected.

Return { action: 'deny' } from setWindowOpenHandler for untrusted content, or supply overrideBrowserWindowOptions so every window option is set explicitly.

If you have any questions or comments about this advisory, email Electron at security@electronjs.org