Microsoft Outlook plug-in PGP version 7.0, 7.0.3, and 7.0.4 silently saves a decrypted copy of a message to hard disk when "Automatically decrypt/verify when opening messages" option is checked, "Always use Secure Viewer when decrypting" option is not checked, and the user replies to an encrypted message.
https://exchange.xforce.ibmcloud.com/vulnerabilities/7900
https://euvd.enisa.europa.eu/vulnerability/EUVD-2002-1676
http://www.securityfocus.com/bid/3825
http://www.ntbugtraq.com/default.asp?pid=36&sid=1&A2=ind0201&L=ntbugtraq&F=P&S=&P=528