This indicates an attempt to exploit a PHP code injection vulnerability in TikiWiki.
The vulnerability is caused by failure to check user input in "tiki-graph_formula.php". It allows remote attackers to execute arbitrary PHP code via the "f" array parameter.
TikiWiki Project, TikiWiki 1.9.8
System Compromise: remote attackers can gain control of vulnerable systems.
Update to version 126.96.36.199,available from the website: