An out-of-bounds write flaw was found in the way Pidgin before 2.12.0 processed XML content. A malicious remote server could potentially use this flaw to crash Pidgin or execute arbitrary code in the context of the pidgin process.
https://www.debian.org/security/2017/dsa-3806
https://security.gentoo.org/glsa/201706-10
https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2017-2640