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Since you don't tell us exactly what the 'older' build was let us just advise you that each and every version of XOOPS up to the 2.0.14 rc1 have built on improving XOOPS security. However, no system is inpenetrable...so you always need to adopt best practices in building and maintaining a site which includes making sure your CHMOD (read write access) is correct, and you only give webmaster permissions to very truted people.
I clicked your site link and can't help you there at all..for me to look at it I require downloaded pluggins which i wasn't prepared to do. Your post does not really make it clear for me at least what hack it is that you are referring to.
Check this
FAQ and go to the FAQ section on 'Upgrades, security and backups' for more information about security. HTH