Asciidoctor-include-ext is Asciidoctor’s standard include processor reimplemented as an extension. Versions prior to 0.4.0, when used to 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! The problem has been patched in the referenced commits.

Affected: RubyGems: asciidoctor-include-ext

### Impact

Applications using [Asciidoctor (Ruby)](https://github.com/asciidoctor/asciidoctor) with [asciidoctor-include-ext](https://github.com/jirutka/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!~~ (EDIT: it’s not)

### Patches

The vulnerability has been fixed in commit c7ea001 (and further improved in cbaccf3), which is included in version [0.4.0](https://rubygems.org/gems/asciidoctor-include-ext/versions/0.4.0).

### Workarounds

```rb 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

### Credits

This vulnerability was discovered by Joern Schneeweisz from the GitLab Security Research Team.

### For more information

See commit message c7ea001.

If you have any questions or comments about this advisory open an issue in [jirutka/asciidoctor-include-ext](https://github.com/jirutka/asciidoctor-include-ext/issues/).

Affected: Ubuntu:20.04:LTS: ruby-asciidoctor-include-ext, Ubuntu:22.04:LTS: ruby-asciidoctor-include-ext, Ubuntu:24.04:LTS: ruby-asciidoctor-include-ext, Ubuntu:25.10: ruby-asciidoctor-include-ext, Ubuntu:26.04:LTS: ruby-asciidoctor-include-ext

Asciidoctor-include-ext is Asciidoctor’s standard include processor reimplemented as an extension. Versions prior to 0.4.0, when used to 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! The problem has been patched in the referenced commits.