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.
{ "availability": "No subscription required", "binaries": [ { "binary_name": "libruby2.3", "binary_version": "2.3.1-2~ubuntu16.04.16" }, { "binary_name": "ruby2.3", "binary_version": "2.3.1-2~ubuntu16.04.16" }, { "binary_name": "ruby2.3-dev", "binary_version": "2.3.1-2~ubuntu16.04.16" }, { "binary_name": "ruby2.3-tcltk", "binary_version": "2.3.1-2~ubuntu16.04.16" } ] }