The remote Debian host is missing a security-related update.
It was discovered that incorrect validation of frame widths in the libvpx multimedia library may result in denial of service and potentially the execution of arbitrary code.
Upgrade the libvpx packages. For the oldstable distribution (jessie), this problem has been fixed in version 1.3.0-3+deb8u1. For the stable distribution (stretch), this problem has been fixed in version 1.6.1-3+deb9u1.