pgp4pine version 1.76 (and possibly below) has a vulnerability to a buffer overflow which allows specially crafted emails the ability to execute arbitrary code on the recipient box when the mail is opened.
You can download this advisory from the following link: https://packetstormsecurity.com/files/download/30900/pgp4pine.txt
Source: https://packetstormsecurity.com/files/30900/pgp4pine.txt.html