CVE-2026-34771: Electron: Use-after-free in WebContents fullscreen, pointer-lock, and keyboard-lock permission callbacks

Apps that register an asynchronous session.setPermissionRequestHandler() may be vulnerable to a use-after-free when handling fullscreen, pointer-lock, or keyboard-lock permission requests. If the requesting frame navigates or the window closes while the permission handler is pending, invoking the stored callback dereferences freed memory, which may lead to a crash or memory corruption.

Apps that do not set a permission request handler, or whose handler responds synchronously, are not affected.