The remote Debian host is missing a security-related update.
Jason Geffner discovered a buffer overflow in the emulated floppy disk drive, resulting in potential privilege escalation.
Upgrade the virtualbox packages. For the oldstable distribution (wheezy), this problem has been fixed in version 4.1.18-dfsg-2+deb7u5. For the stable distribution (jessie), this problem has been fixed in version 4.3.18-dfsg-3+deb8u2.