Fake trackbacks are being made on CAC from non-existent URLs and the link does not have a nofollow rel so it will be assisting spammers. An example page containing trackback spam is http://confluence.atlassian.com/pages/pageinfo.action?pageId=52363319

Some ideas for dealing with this problem
1. Disable trackbacks
2. Append a nofollow rel to all trackbacks so that we aren't boosting these links
3. Add or improve our trackback spam prevention