The remote Debian host is missing a security-related update.
Multiple vulnerabilities were discovered in the interpreter for the Ruby language : - CVE-2015-9096 SMTP command injection in Net::SMTP. - CVE-2016-7798 Incorrect handling of initialization vector in the GCM mode in the OpenSSL extension. - CVE-2017-0900 Denial of service in the RubyGems client. - CVE-2017-0901 Potential file overwrite in the RubyGems client. - CVE-2017-0902 DNS hijacking in the RubyGems client. - CVE-2017-14064 Heap memory disclosure in the JSON library.
Upgrade the ruby2.3 packages. For the stable distribution (stretch), these problems have been fixed in version 2.3.3-1+deb9u1. This update also hardens RubyGems against malicious terminal escape sequences (CVE-2017-0899 ).