Fetchmail versions 4.6.3 through 6.3.16 suffer from a denial of service vulnerability in debug mode.
You can download this advisory from the following link: https://packetstormsecurity.com/files/download/89246/fetchmail-SA-2010-02.txt
Source: https://packetstormsecurity.com/files/89246/Fetchmail-Denial-Of-Service-In-Debug-Mode.html