Potential stack buffer overflow when parsing message as a STUN client

PJSIP is a free and open source multimedia communication library written in C language implementing standard based protocols such as SIP, SDP, RTP, STUN, TURN, and ICE. In versions prior to and including 2.12.1 a stack buffer overflow vulnerability affects PJSIP users that use STUN in their applications, either by: setting a STUN server in their account/media config in PJSUA/PJSUA2 level, or directly using `pjlib-util/stun_simple` API. A patch is available in commit 450baca which should be included in the next release. There are no known workarounds for this issue.