Fetchmail v6.24 and below contains a remote denial of service vulnerability which can be exploited by sending a specially crafted email. Fix available here.
You can download this advisory from the following link: https://packetstormsecurity.com/files/download/31859/fetchmail.6.24.dos.txt
Source: https://packetstormsecurity.com/files/31859/fetchmail.6.24.dos.txt.html