Safe to say WordPress security releases don’t have database upgrades

All the database upgrades can be seen in the code, in the wp-admin/includes/upgrade.php file. And yes, some of the point releases (including 3.5.2) contained “database upgrades”.

Now, it is only very rarely that the actual database schema changes, but there are minor bugfixes in every point release, and sometimes they require a little database action. So while 3.5.2 had seven security related patches, it also contained a fix for multisite installs to fix an invalid site-option. This required a minor bit of code to change the data in the database.

Actual big DB operations almost always are limited to major releases, such as 3.5.0 or 3.4.0 and such, but some minor little bugfixes happen all the time.