Stack-based buffer overflow in Exim 3.35, and other versions before 4, when the sender_verify option is true, allows remote attackers to cause a denial of service and possibly execute arbitrary code during sender verification.
https://exchange.xforce.ibmcloud.com/vulnerabilities/16079
http://www.debian.org/security/2004/dsa-502
http://www.debian.org/security/2004/dsa-501
http://secunia.com/advisories/11558
http://lists.grok.org.uk/pipermail/full-disclosure/2004-May/021015.html