jruby-complete 9.3.8.0 embeds a version of rdoc at ./META-INF/jruby.home/lib/ruby/gems/shared/gems/rdoc-6.1.2.1/ that is subject to CVE-2021-31799.

In RDoc 3.11 through 6.x before 6.3.1, as distributed with Ruby through 3.0.1, it is possible to execute arbitrary code via | and tags in a filename.