The remote Debian host is missing a security-related update.
Huzaifa Sidhpurwala discovered that an out-of-bounds memory write in the codebook parsing code of the Libtremor multimedia library could result in the execution of arbitrary code if a malformed Vorbis file is opened.
Upgrade the libvorbisidec packages. For the oldstable distribution (jessie), this problem has been fixed in version 1.0.2+svn18153-1~deb8u2. For the stable distribution (stretch), this problem has been fixed in version 1.0.2+svn18153-1+deb9u1.