The remote Debian host is missing a security-related update.
Two input sanitization failures have been found in the faxrunq and faxq binaries in mgetty, a smart modem getty replacement. An attacker could leverage them to insert commands via shell metacharacters in jobs id and have them executed with the privilege of the faxrunq/faxq user.
Upgrade the mgetty packages. For the stable distribution (stretch), this problem has been fixed in version 1.1.36-3+deb9u1.