Fetchmail contains a bug that causes an application crash when fetchmail is configured for multidrop mode and the upstream mail server sends a message without headers. As fetchmail does not record this message as “previously fetched”, it will crash with the same message if it is re-executed, so it cannot make progress. A malicious or broken-into upstream server could thus cause a denial of service in fetchmail clients.
You can download this advisory from the following link: https://packetstormsecurity.com/files/download/42642/fetchmail-SA-2005-03.txt
Source: https://packetstormsecurity.com/files/42642/fetchmail-SA-2005-03.txt.html