CVE 2011-0531
demux/mkv/mkv.hpp in the MKV demuxer plugin in VideoLAN VLC media player 1.1.6.1 and earlier allows remote attackers to cause a denial of service (crash) and execute arbitrary commands via a crafted MKV (WebM or Matroska) file that triggers memory corruption, related to "class mismatching" and the MKV_IS_ID macro.
See the 
CVE page on Mitre.org
for more details.
