"The December 2019 Android Security Bulletin has been published by Google and contains details of several vulnerabilities within the Android operating system. In total, three vulnerabilities have been given a critical rating. However, Google has highlighted one of these as being "the most severe," and for very good reason: a single maliciously crafted message could "cause a permanent denial of service." If you tend to hang fire when the "a software update is available" notification lands on your Android smartphone, you might want to hit the "yes" button a bit quicker on this occasion. In fact, I'd recommend installing the December security update just as soon as it is available to you. Unfortunately, not all Android devices receive these security updates, and those that do don't necessarily get them as quickly as they should."