500k are for a remote jailbreak on iOS from the web browser, not just for code execution in the sandboxed browser. So a webkit vulnerability alone will not be enough, you will need to chain multiple 0 days in order to escape the sandbox, and a kernel memory corruption vulnerability to &quot;jailbreak it&quot;. and additionally you will need a codesign vulnerability to run the untether exploit everytime the device boots because the jailbreak is not persistent otherwise.