Well, spammers get better, after blog spamming,
trac is vulnerable.
Creole is using trac for development, and while browsing through tickets, found this:

Public comments and new tickets seem to be suppresed now for anonymus users.
Example:
Ticket: MSSQL driver errors
Edgewall is working on a
spam filter, which will be released with
0.10 Milestone
Until then, disable anonymus content or you can try experimental spam filter.
A quick fix could be:
DELETE FROM ticket_change WHERE author = "spammer_name";
--update ticket version and milestone, which is altered
UPDATE ticket SET version = '', milestone = '' WHERE version = 'HEAD' AND milestone = 'MILESTONE_NAME';