As of Tuesday, 2015-08-11, Adobe AIR is now up to version 22.214.171.124. The update includes 35 security patches. Adobe considers this update to be 'Critical'.
Whenever Adobe Flash is updated, keep an eye out for an AIR update as well, because Flash is incorporated into AIR. Adobe does a lousy job informing people about AIR updates, not even bothering to post on the AIR download page what is the latest version. You literally have to download the most current version and check out the Installer to learn what version you're installing. That's both lazy and stupid of Adobe. :-P