The remote Debian host is missing a security-related update.
Hubert Kario discovered that GnuTLS, a library implementing the TLS and SSL protocols, does not properly decode a status response TLS extension, allowing a remote attacker to cause an application using the GnuTLS library to crash (denial of service).
Upgrade the gnutls28 packages. For the stable distribution (jessie), this problem has been fixed in version 3.3.8-6+deb8u6. For the upcoming stable distribution (stretch), this problem has been fixed in version 3.5.8-5+deb9u1.