libESMTP, probably 1.0.4 and earlier, does not properly handle a '\0' character in a domain name in the subject's Common Name (CN) field of an X.509 certificate, which allows man-in-the-middle attackers to spoof arbitrary SSL servers via a crafted certificate issued by a legitimate Certification Authority, a related issue to CVE-2009-2408.
http://www.vupen.com/english/advisories/2010/1107
http://www.openwall.com/lists/oss-security/2010/03/09/3
http://www.openwall.com/lists/oss-security/2010/03/03/6
http://lists.opensuse.org/opensuse-security-announce/2010-05/msg00001.html