* mkvmerge, mkvinfo, mkvextract, mkvpropedit, MKVToolNix GUI's info tool &
chapter editor: fixed a case of memory being accessed after it had been
freed earlier. This can be triggered by specially crafted Matroska files and
lead to arbitrary code execution. The vulnerability was reported as Cisco
TALOS 2018-0694 on 2018-10-25.