The graph settings script (graph_settings.php) in Cacti 0.8.8b and earlier allows remote attackers to execute arbitrary commands via shell metacharacters in a font size, related to the rrdtool commandline in lib/rrd.php.
Improper Control of Generation of Code The product constructs all or part of a code segment using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the syntax or behavior of the intended code segment.