Stack-based buffer overflow in Exim 4 before 4.33, when the headers_check_syntax option is enabled, allows remote attackers to cause a denial of service and possibly execute arbitrary code during the header check.
https://exchange.xforce.ibmcloud.com/vulnerabilities/16077
http://www.debian.org/security/2004/dsa-502
http://www.debian.org/security/2004/dsa-501
http://lists.grok.org.uk/pipermail/full-disclosure/2004-May/021015.html