The latest Infinispan release in 4.2.x branch is 4.2.1.Final. (http://www.jboss.org/infinispan/downloads.html )
But according to https://issues.jboss.org/browse/ISPN/fixforversion/12316396 there should be one more release with a few important fixes. For instance https://issues.jboss.org/browse/ISPN-1010 is fixed in 4.2.x git branch but there is no release with this fix and this fix is important to have Hibernate timestamps cache properly working. Infinispan 5 and above also have this fixed but it requires Hibernate 4.x version.
We do not plan to do any further 4.2.x releases. You could try porting it to an Infinispan version of your own. Simply clone our git repo, switch to 4.2.x branch, manually apply the patch and build