The sdump function in sdump.c in fetchmail 6.3.11, 6.3.12, and 6.3.13, when running in verbose mode on platforms for which char is signed, allows remote attackers to cause a denial of service (application crash) or possibly execute arbitrary code via an SSL X.509 certificate containing non-printable characters with the high bit set, which triggers a heap-based buffer overflow during escaping.
http://www.vupen.com/english/advisories/2010/0296
http://www.securitytracker.com/id?1023543
http://www.securityfocus.com/bid/38088
http://www.mandriva.com/security/advisories?name=MDVSA-2010:037
http://www.fetchmail.info/fetchmail-SA-2010-01.txt
http://secunia.com/advisories/38391
http://mknod.org/svn/fetchmail/branches/BRANCH_6-3/fetchmail-SA-2010-01.txt