Support for Istio 1.2 ends on December 13th, 2019
According to Istio's support policy, LTS releases like 1.2 are supported for three months after the next LTS release. Since 1.3 was released on September 12th, support for 1.2 will end on December 13th, 2019.
At that point we will stop back-porting fixes for security issues and critical bugs to 1.2, so we encourage you to upgrade to the latest version of Istio (1.5). If you don't do this you may put yourself in the position of having to do a major upgrade on a short timeframe to pick up a critical fix.
We care about you and your clusters, so please be kind to yourself and upgrade.