The remote Debian host is missing a security-related update.
Several vulnerabilities have been discovered in the interpreter for the Ruby language. The Common Vulnerabilities and Exposures project identifies the following problems : - CVE-2018-16395 Tyler Eckstein reported that the equality check of OpenSSL::X509::Name could return true for non-equal objects. If a malicious X.509 certificate is passed to compare with an existing certificate, there is a possibility to be judged incorrectly that they are equal. - CVE-2018-16396 Chris Seaton discovered that tainted flags are not propagated in Array#pack and String#unpack with some directives.
Upgrade the ruby2.3 packages. For the stable distribution (stretch), these problems have been fixed in version 2.3.3-1+deb9u4.