A buffer overflow vulnerability exists in the handling of the MXIT protocol in Pidgin. Specially crafted MXIT data sent from the server could potentially result in arbitrary code execution. A malicious server or an attacker who intercepts the network traffic can send an invalid size for a packet which will trigger a buffer overflow.
https://security.gentoo.org/glsa/201701-38
http://www.ubuntu.com/usn/USN-3031-1
http://www.talosintelligence.com/reports/TALOS-2016-0118/
http://www.securityfocus.com/bid/91335