Ionic V3 Security Issues

Currently we have built 4 mobile apps with Ionic. These are built with Ionic V3. Now Ionic V4 is released, we want to upgrade those apps. However, our planning doesn’t really allow us to upgrade the apps at this moment. The earliest moment we can start upgrading our apps will probably be the 4Q of this year.

But we noticed some new package updates won’t work with Ionic V3. Like @ionic-native/network V5.. doesn’t work with Ionic V3, but @ionic-native/network V4.. does work with Ionic V3. (Due the used Angular and TypeScript versions).

Therefore our question: is it urgent to upgrade to V4, looking at security issues that might be exposed when we do not upgrade those packages?