Anonymous 09/16/2019 (Mon) 13:32:35 No.10626 del
Addendum: the slashes in the example are in the wrong direction.
Using unicode I can craft a filename with what looks to be a forward slash, and looks legitimately so in the file upload field, but still isn't a proper filesystem forward slash and can't be interpreted as such by anything other than the human eye.
Harmless shenanigans.