REXML is an XML toolkit for Ruby. The REXML gem before 3.3.2 has some DoS vulnerabilities when it parses an XML that has many specific characters such as whitespace character, `>]` and `]>`. The REXML gem 3.3.3 or later include the patches to fix these vulnerabilities.
https://www.ruby-lang.org/en/news/2024/08/01/dos-rexml-cve-2024-41123
https://github.com/ruby/rexml/security/advisories/GHSA-vg3r-rm7w-2xgh
https://github.com/ruby/rexml/security/advisories/GHSA-r55c-59qm-vjw6
https://github.com/ruby/rexml/security/advisories/GHSA-4xqq-m2hx-25v8