Denial of service when publishing a package on rubygems.org

Vulnerability Description

Rubygems.org is the Ruby community's gem hosting service. A Gem publisher can cause a Remote DoS when publishing a Gem. This is due to how Ruby reads the Manifest of Gem files when using Gem::Specification.from_yaml. from_yaml makes use of SafeYAML.load which allows YAML aliases inside the YAML-based metadata of a gem. YAML aliases allow for Denial of Service attacks with so-called `YAML-bombs` (comparable to Billion laughs attacks). This was patched. There is is no action required by users. This issue is also tracked as GHSL-2024-001 and was discovered by the GitHub security lab.

References

• https://github.com/rubygems/rubygems.org/security/advisories/GHSA-4vc5-whwr-7hh2
• https://en.wikipedia.org/wiki/Billion_laughs_attack
• https://github.com/ruby/ruby/blob/7cf74a2ff28b1b4c26e367d0d67521f7e1fed239/lib/rubygems/safe_yaml.rb#L28