Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
mainfile.php in XOOPS 22.214.171.124 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.
CWE-22 - Path Traversal
Path traversal (or directory traversal), is a vulnerability that allows malicious users to traverse the server's root directory, gaining access to arbitrary files and folders such as application code & data, back-end credentials, and sensitive operating system files. In the worst-case scenario, an attacker could potentially execute arbitrary files on the server, resulting in a denial of service attack. Such an exploit may severely impact the integrity, confidentiality, and availability of an application.