Off-by-one buffer overflow in spamc of SpamAssassin 2.40 through 2.43, when using BSMTP mode ("-B"), allows remote attackers to execute arbitrary code via email containing headers with leading "." characters.
https://exchange.xforce.ibmcloud.com/vulnerabilities/11154
http://www.securityfocus.com/bid/6679
http://www.securityfocus.com/archive/1/310212/30/26030/threaded
http://www.securityfocus.com/archive/1/309912/30/26090/threaded