Versions of Twiki earlier than 4.2.4 are vulnerable to code execution
due to improper data filtering.
It is recommended to update to the latest version of twiki, currently 4.3.
It should be noted this is a Priority 1, Severity 1 issue.
Priority 1: This vulnerability is the most severe. It is actively being
exploited, or exploitation is imminent. Other outside businesses or
schools are actively being exploited.