diff --git lib/rubygems.rb lib/rubygems.rb
index 4ab0da9acf..f1756cb45d 100644
--- lib/rubygems.rb
+++ lib/rubygems.rb
@@ -10,7 +10,7 @@
 require 'thread'
 
 module Gem
-  VERSION = "2.6.14.3"
+  VERSION = "2.6.14.4"
 end
 
 # Must be first since it unloads the prelude from 1.9.2
diff --git lib/rubygems/command_manager.rb lib/rubygems/command_manager.rb
index 451b719c46..d3ff6614dc 100644
--- lib/rubygems/command_manager.rb
+++ lib/rubygems/command_manager.rb
@@ -7,6 +7,7 @@
 
 require 'rubygems/command'
 require 'rubygems/user_interaction'
+require 'rubygems/text'
 
 ##
 # The command manager registers and installs all the individual sub-commands
@@ -32,6 +33,7 @@
 
 class Gem::CommandManager
 
+  include Gem::Text
   include Gem::UserInteraction
 
   BUILTIN_COMMANDS = [ # :nodoc:
@@ -138,12 +140,12 @@ def command_names
   def run(args, build_args=nil)
     process_args(args, build_args)
   rescue StandardError, Timeout::Error => ex
-    alert_error "While executing gem ... (#{ex.class})\n    #{ex}"
+    alert_error clean_text("While executing gem ... (#{ex.class})\n    #{ex}")
     ui.backtrace ex
 
     terminate_interaction(1)
   rescue Interrupt
-    alert_error "Interrupted"
+    alert_error clean_text("Interrupted")
     terminate_interaction(1)
   end
 
@@ -161,7 +163,7 @@ def process_args(args, build_args=nil)
       say Gem::VERSION
       terminate_interaction 0
     when /^-/ then
-      alert_error "Invalid option: #{args.first}.  See 'gem --help'."
+      alert_error clean_text("Invalid option: #{args.first}. See 'gem --help'.")
       terminate_interaction 1
     else
       cmd_name = args.shift.downcase
@@ -210,7 +212,7 @@ def load_and_instantiate(command_name)
     rescue Exception => e
       e = load_error if load_error
 
-      alert_error "Loading command: #{command_name} (#{e.class})\n\t#{e}"
+      alert_error clean_text("Loading command: #{command_name} (#{e.class})\n\t#{e}")
       ui.backtrace e
     end
   end
diff --git lib/rubygems/commands/owner_command.rb lib/rubygems/commands/owner_command.rb
index 2ee7f84462..7842a322cf 100644
--- lib/rubygems/commands/owner_command.rb
+++ lib/rubygems/commands/owner_command.rb
@@ -2,8 +2,11 @@
 require 'rubygems/command'
 require 'rubygems/local_remote_options'
 require 'rubygems/gemcutter_utilities'
+require 'rubygems/text'
 
 class Gem::Commands::OwnerCommand < Gem::Command
+
+  include Gem::Text
   include Gem::LocalRemoteOptions
   include Gem::GemcutterUtilities
 
@@ -62,7 +65,7 @@ def show_owners name
     end
 
     with_response response do |resp|
-      owners = Gem::SafeYAML.load resp.body
+      owners = Gem::SafeYAML.load clean_text(resp.body)
 
       say "Owners for gem: #{name}"
       owners.each do |owner|
diff --git lib/rubygems/gemcutter_utilities.rb lib/rubygems/gemcutter_utilities.rb
index 7c6d6bb364..623d9301b5 100644
--- lib/rubygems/gemcutter_utilities.rb
+++ lib/rubygems/gemcutter_utilities.rb
@@ -1,11 +1,14 @@
 # frozen_string_literal: true
 require 'rubygems/remote_fetcher'
+require 'rubygems/text'
 
 ##
 # Utility methods for using the RubyGems API.
 
 module Gem::GemcutterUtilities
 
+  include Gem::Text
+
   # TODO: move to Gem::Command
   OptionParser.accept Symbol do |value|
     value.to_sym
@@ -145,13 +148,13 @@ def with_response response, error_prefix = nil
       if block_given? then
         yield response
       else
-        say response.body
+        say clean_text(response.body)
       end
     else
       message = response.body
       message = "#{error_prefix}: #{message}" if error_prefix
 
-      say message
+      say clean_text(message)
       terminate_interaction 1 # TODO: question this
     end
   end
diff --git lib/rubygems/installer.rb lib/rubygems/installer.rb
index 6fd3399dd4..009c138116 100644
--- lib/rubygems/installer.rb
+++ lib/rubygems/installer.rb
@@ -697,9 +697,26 @@ def verify_gem_home(unpack = false) # :nodoc:
       unpack or File.writable?(gem_home)
   end
 
-  def verify_spec_name
-    return if spec.name =~ Gem::Specification::VALID_NAME_PATTERN
-    raise Gem::InstallError, "#{spec} has an invalid name"
+  def verify_spec
+    unless spec.name =~ Gem::Specification::VALID_NAME_PATTERN
+      raise Gem::InstallError, "#{spec} has an invalid name"
+    end
+
+    if spec.raw_require_paths.any?{|path| path =~ /\r\n|\r|\n/ }
+      raise Gem::InstallError, "#{spec} has an invalid require_paths"
+    end
+
+    if spec.extensions.any?{|ext| ext =~ /\r\n|\r|\n/ }
+      raise Gem::InstallError, "#{spec} has an invalid extensions"
+    end
+
+    unless spec.specification_version.to_s =~ /\A\d+\z/
+      raise Gem::InstallError, "#{spec} has an invalid specification_version"
+    end
+
+    if spec.dependencies.any? {|dep| dep.type =~ /\r\n|\r|\n/ || dep.name =~ /\r\n|\r|\n/ }
+      raise Gem::InstallError, "#{spec} has an invalid dependencies"
+    end
   end
 
   ##
@@ -826,10 +843,12 @@ def dir
   def pre_install_checks
     verify_gem_home options[:unpack]
 
+    # The name and require_paths must be verified first, since it could contain
+    # ruby code that would be eval'ed in #ensure_loadable_spec
+    verify_spec
+
     ensure_loadable_spec
 
-    verify_spec_name
-
     if options[:install_as_default]
       Gem.ensure_default_gem_subdirectories gem_home
     else
diff --git lib/rubygems/package.rb lib/rubygems/package.rb
index 1dd28d8132..d2cbd09134 100644
--- lib/rubygems/package.rb
+++ lib/rubygems/package.rb
@@ -425,6 +425,16 @@ def install_location filename, destination_dir # :nodoc:
     raise Gem::Package::PathError.new(destination, destination_dir) unless
       destination.start_with? destination_dir + '/'
 
+    begin
+      real_destination = File.expand_path(File.realpath(destination))
+    rescue
+      # it's fine if the destination doesn't exist, because rm -rf'ing it can't cause any damage
+      nil
+    else
+      raise Gem::Package::PathError.new(real_destination, destination_dir) unless
+        real_destination.start_with? destination_dir + '/'
+    end
+
     destination.untaint
     destination
   end
diff --git lib/rubygems/user_interaction.rb lib/rubygems/user_interaction.rb
index 390d0f2aea..237ae2bc71 100644
--- lib/rubygems/user_interaction.rb
+++ lib/rubygems/user_interaction.rb
@@ -6,6 +6,7 @@
 #++
 
 require 'rubygems/util'
+require 'rubygems/text'
 
 begin
   require 'io/console'
@@ -18,6 +19,8 @@
 
 module Gem::DefaultUserInteraction
 
+  include Gem::Text
+
   ##
   # The default UI is a class variable of the singleton class for this
   # module.
@@ -165,8 +168,8 @@ def terminate_interaction exit_code = 0
   # Calls +say+ with +msg+ or the results of the block if really_verbose
   # is true.
 
-  def verbose msg = nil
-    say(msg || yield) if Gem.configuration.really_verbose
+  def verbose(msg = nil)
+    say(clean_text(msg || yield)) if Gem.configuration.really_verbose
   end
 end
 
diff --git test/rubygems/test_gem_installer.rb test/rubygems/test_gem_installer.rb
index dd049214fb..4f84a9d6a4 100644
--- test/rubygems/test_gem_installer.rb
+++ test/rubygems/test_gem_installer.rb
@@ -1468,6 +1468,112 @@ def spec.validate; end
     end
   end
 
+  def test_pre_install_checks_malicious_name_before_eval
+    spec = util_spec "malicious\n::Object.const_set(:FROM_EVAL, true)#", '1'
+    def spec.full_name # so the spec is buildable
+      "malicious-1"
+    end
+    def spec.validate(*args); end
+
+    util_build_gem spec
+
+    gem = File.join(@gemhome, 'cache', spec.file_name)
+
+    use_ui @ui do
+      @installer = Gem::Installer.at gem
+      e = assert_raises Gem::InstallError do
+        @installer.pre_install_checks
+      end
+      assert_equal "#<Gem::Specification name=malicious\n::Object.const_set(:FROM_EVAL, true)# version=1> has an invalid name", e.message
+    end
+    refute defined?(::Object::FROM_EVAL)
+  end
+
+  def test_pre_install_checks_malicious_require_paths_before_eval
+    spec = util_spec "malicious", '1'
+    def spec.full_name # so the spec is buildable
+      "malicious-1"
+    end
+    def spec.validate(*args); end
+    spec.require_paths = ["malicious\n``"]
+
+    util_build_gem spec
+
+    gem = File.join(@gemhome, 'cache', spec.file_name)
+
+    use_ui @ui do
+      @installer = Gem::Installer.at gem
+      e = assert_raises Gem::InstallError do
+        @installer.pre_install_checks
+      end
+      assert_equal "#<Gem::Specification name=malicious version=1> has an invalid require_paths", e.message
+    end
+  end
+
+  def test_pre_install_checks_malicious_extensions_before_eval
+    spec = util_spec "malicious", '1'
+    def spec.full_name # so the spec is buildable
+      "malicious-1"
+    end
+    def spec.validate(*args); end
+    spec.extensions = ["malicious\n``"]
+
+    util_build_gem spec
+
+    gem = File.join(@gemhome, 'cache', spec.file_name)
+
+    use_ui @ui do
+      @installer = Gem::Installer.at gem
+      e = assert_raises Gem::InstallError do
+        @installer.pre_install_checks
+      end
+      assert_equal "#<Gem::Specification name=malicious version=1> has an invalid extensions", e.message
+    end
+  end
+
+  def test_pre_install_checks_malicious_specification_version_before_eval
+    spec = util_spec "malicious", '1'
+    def spec.full_name # so the spec is buildable
+      "malicious-1"
+    end
+    def spec.validate(*args); end
+    spec.specification_version = "malicious\n``"
+
+    util_build_gem spec
+
+    gem = File.join(@gemhome, 'cache', spec.file_name)
+
+    use_ui @ui do
+      @installer = Gem::Installer.at gem
+      e = assert_raises Gem::InstallError do
+        @installer.pre_install_checks
+      end
+      assert_equal "#<Gem::Specification name=malicious version=1> has an invalid specification_version", e.message
+    end
+  end
+
+  def test_pre_install_checks_malicious_dependencies_before_eval
+    spec = util_spec "malicious", '1'
+    def spec.full_name # so the spec is buildable
+      "malicious-1"
+    end
+    def spec.validate(*args); end
+    spec.add_dependency "b\nfoo", '> 5'
+
+    util_build_gem spec
+
+    gem = File.join(@gemhome, 'cache', spec.file_name)
+
+    use_ui @ui do
+      @installer = Gem::Installer.at gem
+      @installer.ignore_dependencies = true
+      e = assert_raises Gem::InstallError do
+        @installer.pre_install_checks
+      end
+      assert_equal "#<Gem::Specification name=malicious version=1> has an invalid dependencies", e.message
+    end
+  end
+
   def test_shebang
     util_make_exec @spec, "#!/usr/bin/ruby"
 
diff --git test/rubygems/test_gem_package.rb test/rubygems/test_gem_package.rb
index 713c84d700..5fa90958a2 100644
--- test/rubygems/test_gem_package.rb
+++ test/rubygems/test_gem_package.rb
@@ -480,6 +480,42 @@ def test_extract_symlink_parent
                  "#{destination_subdir} is not allowed", e.message)
   end
 
+  def test_extract_symlink_parent_doesnt_delete_user_dir
+    skip if RUBY_VERSION <= "1.8.7"
+
+    package = Gem::Package.new @gem
+
+    # Extract into a subdirectory of @destination; if this test fails it writes
+    # a file outside destination_subdir, but we want the file to remain inside
+    # @destination so it will be cleaned up.
+    destination_subdir = File.join @destination, 'subdir'
+    FileUtils.mkdir_p destination_subdir
+
+    destination_user_dir = File.join @destination, 'user'
+    destination_user_subdir = File.join destination_user_dir, 'dir'
+    FileUtils.mkdir_p destination_user_subdir
+
+    tgz_io = util_tar_gz do |tar|
+      tar.add_symlink 'link', destination_user_dir, 16877
+      tar.add_symlink 'link/dir', '.', 16877
+    end
+
+    e = assert_raises(Gem::Package::PathError, Errno::EACCES) do
+      package.extract_tar_gz tgz_io, destination_subdir
+    end
+
+    assert_path_exists destination_user_subdir
+
+    if Gem::Package::PathError === e
+      assert_equal("installing into parent path #{destination_user_subdir} of " +
+                  "#{destination_subdir} is not allowed", e.message)
+    elsif win_platform?
+      skip "symlink - must be admin with no UAC on Windows"
+    else
+      raise e
+    end
+  end
+
   def test_extract_tar_gz_directory
     package = Gem::Package.new @gem