[USN-3553-1] Ruby vulnerabilities

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Ubuntu Security Notice USN-3553-1
January 31, 2018

ruby2.3 vulnerabilities
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A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 17.10
- Ubuntu 16.04 LTS

Summary:

Several security issues were fixed in Ruby.

Software Description:
- ruby2.3: Interpreter of object-oriented scripting language Ruby

Details:

It was discovered that Ruby failed to validate specification names.
An attacker could possibly use a maliciously crafted gem to potentially
overwrite any file on the filesystem. (CVE-2017-0901)

It was discovered that Ruby was vulnerable to a DNS hijacking
vulnerability. An attacker could use this to possibly force the
RubyGems client to download and install gems from a server that the
attacker controls. (CVE-2017-0902)

It was discovered that Ruby incorrectly handled certain YAML files. An
attacker could use this to possibly execute arbitrary code. 
(CVE-2017-0903)

Update instructions:

The problem can be corrected by updating your system to the following
package versions:

Ubuntu 17.10:
  libruby2.3                      2.3.3-1ubuntu1.3
  ruby2.3                         2.3.3-1ubuntu1.3

Ubuntu 16.04 LTS:
  libruby2.3                      2.3.1-2~16.04.6
  ruby2.3                         2.3.1-2~16.04.6

In general, a standard system update will make all the necessary
changes.

References:
  https://www.ubuntu.com/usn/usn-3553-1
  CVE-2017-0901, CVE-2017-0902, CVE-2017-0903

Package Information:
  https://launchpad.net/ubuntu/+source/ruby2.3/2.3.3-1ubuntu1.3
  https://launchpad.net/ubuntu/+source/ruby2.3/2.3.1-2~16.04.6