The remote Debian host is missing a security-related update.
Multiple vulnerabilities have been discovered in Asterisk, an open source PBX and telephony toolkit, which may result in denial of service, information disclosure and potentially the execution of arbitrary code.
Upgrade the asterisk packages. For the oldstable distribution (jessie), these problems have been fixed in version 1:11.13.1~dfsg-2+deb8u5. For the stable distribution (stretch), these problems have been fixed in version 1:13.14.1~dfsg-2+deb9u3.