fetchmail 6.3.5 and 6.3.6 before 6.3.6-rc4, when refusing a message delivered via the mda option, allows remote attackers to cause a denial of service (crash) via unknown vectors that trigger a NULL pointer dereference when calling the (1) ferror or (2) fflush functions.
http://www.vupen.com/english/advisories/2007/0088
http://www.vupen.com/english/advisories/2007/0087
http://www.trustix.org/errata/2007/0007
http://www.securityfocus.com/bid/21902
http://www.securityfocus.com/archive/1/456114/100/0/threaded
http://www.openpkg.com/security/advisories/OpenPKG-SA-2007.004.html
http://www.novell.com/linux/security/advisories/2007_4_sr.html
http://slackware.com/security/viewer.php?l=slackware-security&y=2007&m=slackware-security.517995
http://securitytracker.com/id?1017479
http://security.gentoo.org/glsa/glsa-200701-13.xml
http://secunia.com/advisories/24151
http://secunia.com/advisories/23923
http://secunia.com/advisories/23838
http://secunia.com/advisories/23804
http://secunia.com/advisories/23631