Interpretation conflict in PostNuke 0.761 and earlier allows remote attackers to conduct cross-site scripting (XSS) attacks via HTML tags with a trailing "<" character, which is interpreted as a ">" character by some web browsers but bypasses the blacklist protection in (1) the pnVarCleanFromInput function in pnAPI.php, (2) the pnSecureInput function in pnAntiCracker.php, and (3) the htmltext parameter in an edituser operation to user.php.

Cross-site scripting (XSS) vulnerability in PostNuke 0.71 and earlier allows remote attackers to inject arbitrary web script or HTML via the (1) name parameter in modules.php and (2) catid parameter in index.php.

Cross-site scripting vulnerabilities in PostBoard 2.0.1 and earlier allows remote attackers to execute script as other users via (1) an [IMG] tag when BBCode is enabled, or (2) in a topic title.