The remote Debian host is missing a security-related update.
The Qualys Research Labs discovered various problems in the dynamic linker of the GNU C Library which allow local privilege escalation by clashing the stack. For the full details, please refer to their advisory published at: https://www.qualys.com/2017/06/19/stack-clash/stack-clash.txt
Upgrade the glibc packages. For the oldstable distribution (jessie), this problem has been fixed in version 2.19-18+deb8u10. For the stable distribution (stretch), this problem has been fixed in version 2.24-11+deb9u1.