libav - security update

It was discovered that there was a use-after free vulnerability in
libav, a multimedia player, server, encoder and transcoder library.

The seg_write_packet function in libavformat/segment.c in ffmpeg
2.1.4 and earlier does not free the correct memory location, which
allows remote attackers to cause a denial of service (“invalid
memory handler”) and possibly execute arbitrary code via a crafted
video that triggers a use after free.

For Debian 7 Wheezy, this issue has been fixed in libav version
6:0.8.17-2+deb7u1.

We recommend that you upgrade your libav packages.