The activation resend function in the Profiles module in XOOPS before 2.4.1 sends activation codes in response to arbitrary activation requests, which allows remote attackers to bypass administrative approval via a request involving activate.php.

Multiple unspecified vulnerabilities in XOOPS before 2.4.0 Final have unknown impact and attack vectors.

mainfile.php in XOOPS 2.0.13.2 and earlier, when register_globals is enabled, allows remote attackers to overwrite variables such as $xoopsOption['nocommon'] and conduct directory traversal attacks or include PHP files via (1) xoopsConfig[language] to misc.php or (2) xoopsConfig[theme_set] to index.php, as demonstrated by injecting PHP sequences into a log file.