The NSS plugin in libpurple in Pidgin 2.4.3 does not verify SSL certificates, which makes it easier for remote attackers to trick a user into accepting an invalid server certificate for a spoofed service.
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A18327
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A10979
https://exchange.xforce.ibmcloud.com/vulnerabilities/44220
http://www.vupen.com/english/advisories/2008/2318
http://www.ubuntu.com/usn/USN-675-1
http://www.securityfocus.com/bid/30553
http://www.redhat.com/support/errata/RHSA-2008-1023.html
http://www.mandriva.com/security/advisories?name=MDVSA-2009:025
http://support.avaya.com/elmodocs2/security/ASA-2008-493.htm
http://secunia.com/advisories/33102
http://secunia.com/advisories/32859
http://secunia.com/advisories/31390
http://developer.pidgin.im/ticket/6500
http://developer.pidgin.im/attachment/ticket/6500/nss_add_rev.patch