family_feedbag.c in the oscar protocol plugin in libpurple in Pidgin before 2.10.1 does not perform the expected UTF-8 validation on message data, which allows remote attackers to cause a denial of service (application crash) via a crafted (1) AIM or (2) ICQ message associated with buddy-list addition.
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A18408
https://hermes.opensuse.org/messages/13195955
http://www.securityfocus.com/bid/51010
http://www.redhat.com/support/errata/RHSA-2011-1821.html
http://www.redhat.com/support/errata/RHSA-2011-1820.html
http://www.openwall.com/lists/oss-security/2011/12/10/2
http://www.openwall.com/lists/oss-security/2011/12/10/1
http://www.mandriva.com/security/advisories?name=MDVSA-2011:183
http://secunia.com/advisories/47234
http://secunia.com/advisories/47219
http://pidgin.im/news/security/?id=57
http://developer.pidgin.im/viewmtn/revision/info/757272a78a8ca6027d518e614712c3399e34dda3