Update your iPhone immediately. Apple has released the iOS 14.4 update with fixes to three critical security gaps which are probably known.
Apple did not provide too many details about the bugs, except that "they may have already been used." 
One vulnerability even affects the kernel, and an attacker could elevate their privilege level (such as becoming an administrator) to cause serious damage to your device or steal your data you.
The two other vulnerabilities affect Apple's WebKit rendering engine that powers Safari. They allow attackers to run arbitrary code that could be used to track you. We don't know if this can be done remotely or if the attacker needs to physics access to the device.
Over time, we may learn more about these security holes, but for now it's important to update your iPhone to iOS 14.4 right away.
To do this, go to Settings – General – Software Update and do λήψη of the updated version.
