The XMPP protocol plugin in libpurple in Pidgin before 2.6.2 does not properly handle an error IQ stanza during an attempted fetch of a custom smiley, which allows remote attackers to cause a denial of service (application crash) via XHTML-IM content with cid: images.
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A6434
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A11223
http://www.securityfocus.com/bid/36277
http://www.pidgin.im/news/security/index.php?id=37
http://secunia.com/advisories/36601
http://developer.pidgin.im/viewmtn/revision/info/fd5955618eddcd84d522b30ff11102f9601f38c8