The remote Debian host is missing a security-related update.
An integer overflow has been found in the HTTP range module of Nginx, a high-performance web and reverse proxy server, which may result in information disclosure.
Upgrade the nginx packages. For the oldstable distribution (jessie), this problem has been fixed in version 1.6.2-5+deb8u5. For the stable distribution (stretch), this problem has been fixed in version 1.10.3-1+deb9u1.