MIVA Merchant 5 is vulnerable to XSS attack. Users can use javascript to embed their own inputs into the MM5 screens and checkout pages overriding various store safeguards and functions.

MIVA Corporation has been very cooperative and has already posted an update to their software entitled (core-4). Users of MIVA Merchant 5 should login to their admin panels and allow the update wizard to make the current updates to (core-4). An earlier patch entitled (core-2) should be installed prior to installing (core-4).

The update includes the sanity checking and cleanup of several key variables and fixes other security issues found with the new templating system.

XSS Sample:
http://HOSTNAME/mm5/merchant.mvc?Screen=ACNT&Action=EMPW&Customer_Login="><script>document.write("\n<br><input%20type=text%20name=somenewfield%20value='Hello%20World'>")</script>