Oracle Linux: CVE-2021-28965: ELSA-2021-2584: ruby:2.7 security, bug fix, and enhancement update (MODERATE) (Multiple Advisories)

The REXML gem before 3.2.5 in Ruby before 2.6.7, 2.7.x before 2.7.3, and 3.x before 3.0.1 does not properly address XML round-trip issues. An incorrect document can be produced after parsing and serializing.
A flaw was found in the way the Ruby REXML library parsed XML documents. Parsing a specially crafted XML document using REXML and writing parsed data back to a new XML document results in creating a document with a different structure. This issue could affect the integrity of processed data in applications using REXML that parse XML documents, write data back to XML, and re-parse them again.