The com_rss option (rss.php) in (1) Mambo and (2) Joomla! allows remote attackers to cause a denial of service (disk consumption and possibly web-server outage) via multiple requests with different values of the feed parameter.
Improper Input Validation The product receives input or data, but it does
not validate or incorrectly validates that the input has the
properties that are required to process the data safely and
correctly.