The XMPP protocol plugin in libpurple in Pidgin before 2.10.8 does not properly determine whether the from address in an iq reply is consistent with the to address in an iq request, which allows remote attackers to spoof iq traffic or cause a denial of service (NULL pointer dereference and application crash) via a crafted reply.
https://rhn.redhat.com/errata/RHSA-2014-0139.html
http://www.ubuntu.com/usn/USN-2100-1
http://www.debian.org/security/2014/dsa-2859
http://pidgin.im/news/security/?id=78
http://lists.opensuse.org/opensuse-updates/2014-03/msg00005.html
http://lists.opensuse.org/opensuse-updates/2014-02/msg00039.html