diff --git a/Dockerfile b/Dockerfile
index c5a0979..9979ce7 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -58,6 +58,8 @@ RUN apk update \
     && rm -rf /usr/local/lib/ruby/gems/*/specifications/default/cgi-*.gemspec \
     && rm -rf /usr/local/lib/ruby/gems/*/gems/stringio-* \
     && rm -rf /usr/local/lib/ruby/gems/*/specifications/default/stringio-*.gemspec \
+    && rm -rf /usr/local/lib/ruby/gems/*/gems/rdoc-* \
+    && rm -rf /usr/local/lib/ruby/gems/*/specifications/default/rdoc-*.gemspec \
     && rm -rf /usr/local/lib/ruby/gems/*/gems/rexml-* \
     && rm -rf /usr/local/lib/ruby/gems/*/specifications/rexml-*.gemspec
 
diff --git a/voxbox/Gemfile b/voxbox/Gemfile
index ab9c525..9b6ea34 100644
--- a/voxbox/Gemfile
+++ b/voxbox/Gemfile
@@ -18,5 +18,5 @@ gem 'ffi', '~> 1.16.3' # ffi 1.17.0 has change dependencies - see https://github
 gem 'cgi', '~> 0.4.1'             # cgi 0.1.0 has CVEs - remove default and install upstream replacement
 gem 'stringio', '~> 3.1'          # stringio 0.1.0 has CVEs - remove default and install upstream replacement
 gem 'rexml', '~> 3.3', '>= 3.3.6' # rexml < 3.3 has CVEs - remove default and install upstream replacement
-
+gem 'rdoc', '~> 6.7'             # rdoc 6.2.1 has CVEs - remove default and install upstream replacement
 # vim: syntax=ruby