You can declare a cargo table with a field of type URL. You can then store urls like javascript:alert(1) in them. These urls can be malicious and a user could be tricked into clicking on them. Cargo should probably not allow storing javascript: scheme urls

Note: Its notoriously difficult to blacklist javascript: protocol urls, because browsers accept lots of variants. MediaWiki usually solves this problem by whitelisting good url protocols, although i don't know if cargo considers it acceptable to only allow a small set of good urls. Maybe cargo should allow everything, but only automatically link things that meet wfUrlProtocols();