As you can check on
https://test.wikipedia.org/wiki/Special:AbuseFilter/tools
ccnorm("BAD")!==ccnorm("BAD")
where the first string has just 3 characters and the second one has a few invisible characters inside it.
Therefore, anyone can fool abuse filters which try to avoid ofenses, badwords, etc.. by just copying invisible characters in the text.
Version: unspecified
Severity: normal
To fix this, we would either need to add these characters to AntiSpoof's maintenance/equivset.in (and make them normalize to and empty string) or, if that's not possible/ desired, we could also extend our own ccnorm function.
Change 117640 had a related patch set uploaded by Hoo man:
Map U+200B (zero width space) to an empty string
Change 117640 merged by jenkins-bot:
Map U+200B (zero width space) to an empty string