Asterisk Project Security Advisory – When handling an INVITE with Replaces message the res_pjsip_refer module incorrectly assumes that it will be operating on a channel that has just been created. If the INVITE with Replaces message is sent in-dialog after a session has been established this assumption will be incorrect. The res_pjsip_refer module will then hang up a channel that is actually owned by another thread. When this other thread attempts to use the just hung up channel it will end up using freed channel which will likely cause a crash.