Untill Phil posts...
In x-cart v4.6.6 it looks like the security update affected 2 reBOOT files which will have to be manually patched.
\skin\reboot\modules\Customer_Reviews\vote_reviews .tpl
\skin\reboot\customer\main\address_box.tpl
Compare the original x-cart version vs the security version to see what changes took place and then manually patch the reBOOT version of the files.
Use a file comparison tool like Beyond Compare
http://www.scootersoftware.com/