In GNOME Shell through 45.2, unauthenticated remote code execution can be achieved by intercepting two DNS requests (GNOME Network Manager and GNOME Shell Portal Helper connectivity checks), and responding with attacker-specific IP addresses. This DNS hijacking causes GNOME Captive Portal to be launched via a WebKitGTK browser, by default, on the victim system; this can run JavaScript code inside a sandbox. NOTE: the vendor's position is that this is not a vulnerability because running JavaScript code inside a sandbox is the intended behavior.