Command Injection vulnerability in asciidoctor-include-ext

Impact

Applications using Asciidoctor (Ruby)
with asciidoctor-include-ext
(prior to version 0.4.0), which render user-supplied input in AsciiDoc markup, may
allow an attacker to execute arbitrary system commands on the host operating system.
This attack is possible even when allow-uri-read is disabled!

Patches

The vulnerability has been fixed in commit c7ea001 (and further improved in cbaccf3),
which is included in version
0.4.0.

Workarounds

require 'asciidoctor/include_ext'

class Asciidoctor::IncludeExt::IncludeProcessor
  # Overrides superclass private method to mitigate Command Injection
  # vulnerability in asciidoctor-include-ext <0.4.0.
  def target_uri?(target)
    target.downcase.start_with?('http://', 'https://') \
      && URI.parse(target).is_a?(URI::HTTP)
  rescue URI::InvalidURIError
    false
  end
end

References

• https://sakurity.com/blog/2015/02/28/openuri.html