diff --git lib/rubygems.rb lib/rubygems.rb
index 04031c765c..9c0219ce06 100644
--- lib/rubygems.rb
+++ lib/rubygems.rb
@@ -10,7 +10,7 @@
 require 'thread'
 
 module Gem
-  VERSION = '2.5.2'
+  VERSION = '2.5.2.1'
 end
 
 # Must be first since it unloads the prelude from 1.9.2
diff --git lib/rubygems/commands/query_command.rb lib/rubygems/commands/query_command.rb
index d6196b44ed..61e9808860 100644
--- lib/rubygems/commands/query_command.rb
+++ lib/rubygems/commands/query_command.rb
@@ -226,7 +226,7 @@ def output_versions output, versions
         end
       end
 
-      output << make_entry(matching_tuples, platforms)
+      output << clean_text(make_entry(matching_tuples, platforms))
     end
   end
 
@@ -344,7 +344,8 @@ def spec_platforms entry, platforms
   end
 
   def spec_summary entry, spec
-    entry << "\n\n" << format_text(spec.summary, 68, 4)
+    summary = truncate_text(spec.summary, "the summary for #{spec.full_name}")
+    entry << "\n\n" << format_text(summary, 68, 4)
   end
 
 end
diff --git lib/rubygems/installer.rb lib/rubygems/installer.rb
index 85358e0d1a..709b77d126 100644
--- lib/rubygems/installer.rb
+++ lib/rubygems/installer.rb
@@ -693,6 +693,11 @@ 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"
+  end
+
   ##
   # Return the text for an application file.
 
@@ -812,6 +817,8 @@ def pre_install_checks
 
     ensure_loadable_spec
 
+    verify_spec_name
+
     if options[:install_as_default]
       Gem.ensure_default_gem_subdirectories gem_home
     else
diff --git lib/rubygems/remote_fetcher.rb lib/rubygems/remote_fetcher.rb
index fda1e067ef..254bebfadf 100644
--- lib/rubygems/remote_fetcher.rb
+++ lib/rubygems/remote_fetcher.rb
@@ -104,7 +104,7 @@ def api_endpoint(uri)
     else
       target = res.target.to_s.strip
 
-      if /\.#{Regexp.quote(host)}\z/ =~ target
+      if URI("http://" + target).host.end_with?(".#{host}")
         return URI.parse "#{uri.scheme}://#{target}#{uri.path}"
       end
 
diff --git lib/rubygems/specification.rb lib/rubygems/specification.rb
index 8e2557cdb2..dd4fde1776 100644
--- lib/rubygems/specification.rb
+++ lib/rubygems/specification.rb
@@ -108,6 +108,8 @@ class Gem::Specification < Gem::BasicSpecification
 
   private_constant :LOAD_CACHE if defined? private_constant
 
+  VALID_NAME_PATTERN = /\A[a-zA-Z0-9\.\-\_]+\z/ # :nodoc:
+
   # :startdoc:
 
   ##
@@ -2665,9 +2667,15 @@ def validate packaging = true
       end
     end
 
-    unless String === name then
+    if !name.is_a?(String) then
       raise Gem::InvalidSpecificationException,
-            "invalid value for attribute name: \"#{name.inspect}\""
+            "invalid value for attribute name: \"#{name.inspect}\" must be a string"
+    elsif name !~ /[a-zA-Z]/ then
+      raise Gem::InvalidSpecificationException,
+            "invalid value for attribute name: #{name.dump} must include at least one letter"
+    elsif name !~ VALID_NAME_PATTERN then
+      raise Gem::InvalidSpecificationException,
+            "invalid value for attribute name: #{name.dump} can only include letters, numbers, dashes, and underscores"
     end
 
     if raw_require_paths.empty? then
diff --git lib/rubygems/text.rb lib/rubygems/text.rb
index 732f1b99f2..b944b62c27 100644
--- lib/rubygems/text.rb
+++ lib/rubygems/text.rb
@@ -6,13 +6,26 @@
 
 module Gem::Text
 
+  ##
+  # Remove any non-printable characters and make the text suitable for
+  # printing.
+  def clean_text(text)
+    text.gsub(/[\000-\b\v-\f\016-\037\177]/, ".".freeze)
+  end
+
+  def truncate_text(text, description, max_length = 100_000)
+    raise ArgumentError, "max_length must be positive" unless max_length > 0
+    return text if text.size <= max_length
+    "Truncating #{description} to #{max_length.to_s.reverse.gsub(/...(?=.)/,'\&,').reverse} characters:\n" + text[0, max_length]
+  end
+
   ##
   # Wraps +text+ to +wrap+ characters and optionally indents by +indent+
   # characters
 
   def format_text(text, wrap, indent=0)
     result = []
-    work = text.dup
+    work = clean_text(text)
 
     while work.length > wrap do
       if work =~ /^(.{0,#{wrap}})[ \n]/ then
diff --git test/rubygems/test_gem_commands_query_command.rb test/rubygems/test_gem_commands_query_command.rb
index 78c15a1770..9ec715492f 100644
--- test/rubygems/test_gem_commands_query_command.rb
+++ test/rubygems/test_gem_commands_query_command.rb
@@ -116,6 +116,86 @@ def test_execute_details
     This is a lot of text. This is a lot of text. This is a lot of text.
     This is a lot of text.
 
+pl (1)
+    Platform: i386-linux
+    Author: A User
+    Homepage: http://example.com
+
+    this is a summary
+    EOF
+
+    assert_equal expected, @ui.output
+    assert_equal '', @ui.error
+  end
+
+  def test_execute_details_cleans_text
+    spec_fetcher do |fetcher|
+      fetcher.spec 'a', 2 do |s|
+        s.summary = 'This is a lot of text. ' * 4
+        s.authors = ["Abraham Lincoln \x01", "\x02 Hirohito"]
+        s.homepage = "http://a.example.com/\x03"
+      end
+
+      fetcher.legacy_platform
+    end
+
+    @cmd.handle_options %w[-r -d]
+
+    use_ui @ui do
+      @cmd.execute
+    end
+
+    expected = <<-EOF
+
+*** REMOTE GEMS ***
+
+a (2)
+    Authors: Abraham Lincoln ., . Hirohito
+    Homepage: http://a.example.com/.
+
+    This is a lot of text. This is a lot of text. This is a lot of text.
+    This is a lot of text.
+
+pl (1)
+    Platform: i386-linux
+    Author: A User
+    Homepage: http://example.com
+
+    this is a summary
+    EOF
+
+    assert_equal expected, @ui.output
+    assert_equal '', @ui.error
+  end
+
+  def test_execute_details_truncates_summary
+    spec_fetcher do |fetcher|
+      fetcher.spec 'a', 2 do |s|
+        s.summary = 'This is a lot of text. ' * 10_000
+        s.authors = ["Abraham Lincoln \x01", "\x02 Hirohito"]
+        s.homepage = "http://a.example.com/\x03"
+      end
+
+      fetcher.legacy_platform
+    end
+
+    @cmd.handle_options %w[-r -d]
+
+    use_ui @ui do
+      @cmd.execute
+    end
+
+    expected = <<-EOF
+
+*** REMOTE GEMS ***
+
+a (2)
+    Authors: Abraham Lincoln ., . Hirohito
+    Homepage: http://a.example.com/.
+
+    Truncating the summary for a-2 to 100,000 characters:
+#{"    This is a lot of text. This is a lot of text. This is a lot of text.\n" * 1449}    This is a lot of te
+
 pl (1)
     Platform: i386-linux
     Author: A User
diff --git test/rubygems/test_gem_installer.rb test/rubygems/test_gem_installer.rb
index 5ec71d0a01..1092a0c68f 100644
--- test/rubygems/test_gem_installer.rb
+++ test/rubygems/test_gem_installer.rb
@@ -1227,6 +1227,26 @@ def test_pre_install_checks_wrong_rubygems_version
     end
   end
 
+  def test_pre_install_checks_malicious_name
+    spec = util_spec '../malicious', '1'
+    def spec.full_name # so the spec is buildable
+      "malicious-1"
+    end
+    def spec.validate; 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 version=1> has an invalid name', e.message
+    end
+  end
+
   def test_shebang
     util_make_exec @spec, "#!/usr/bin/ruby"
 
diff --git test/rubygems/test_gem_remote_fetcher.rb test/rubygems/test_gem_remote_fetcher.rb
index 49b6b6656c..a3919c8ef2 100644
--- test/rubygems/test_gem_remote_fetcher.rb
+++ test/rubygems/test_gem_remote_fetcher.rb
@@ -253,6 +253,21 @@ def test_api_endpoint_ignores_trans_domain_values_that_end_with_original
     dns.verify
   end
 
+  def test_api_endpoint_ignores_trans_domain_values_that_end_with_original_in_path
+    uri = URI.parse "http://example.com/foo"
+    target = MiniTest::Mock.new
+    target.expect :target, "evil.com/a.example.com"
+
+    dns = MiniTest::Mock.new
+    dns.expect :getresource, target, [String, Object]
+
+    fetch = Gem::RemoteFetcher.new nil, dns
+    assert_equal URI.parse("http://example.com/foo"), fetch.api_endpoint(uri)
+
+    target.verify
+    dns.verify
+  end
+
   def test_api_endpoint_timeout_warning
     uri = URI.parse "http://gems.example.com/foo"
 
diff --git test/rubygems/test_gem_specification.rb test/rubygems/test_gem_specification.rb
index bc1c8d2ca7..9a49bbbf59 100644
--- test/rubygems/test_gem_specification.rb
+++ test/rubygems/test_gem_specification.rb
@@ -2974,7 +2974,37 @@ def test_validate_name
       @a1.validate
     end
 
-    assert_equal 'invalid value for attribute name: ":json"', e.message
+    assert_equal 'invalid value for attribute name: ":json" must be a string', e.message
+
+    @a1.name = []
+    e = assert_raises Gem::InvalidSpecificationException do
+      @a1.validate
+    end
+    assert_equal "invalid value for attribute name: \"[]\" must be a string", e.message
+
+    @a1.name = ""
+    e = assert_raises Gem::InvalidSpecificationException do
+      @a1.validate
+    end
+    assert_equal "invalid value for attribute name: \"\" must include at least one letter", e.message
+
+    @a1.name = "12345"
+    e = assert_raises Gem::InvalidSpecificationException do
+      @a1.validate
+    end
+    assert_equal "invalid value for attribute name: \"12345\" must include at least one letter", e.message
+
+    @a1.name = "../malicious"
+    e = assert_raises Gem::InvalidSpecificationException do
+      @a1.validate
+    end
+    assert_equal "invalid value for attribute name: \"../malicious\" can only include letters, numbers, dashes, and underscores", e.message
+
+    @a1.name = "\ba\t"
+    e = assert_raises Gem::InvalidSpecificationException do
+      @a1.validate
+    end
+    assert_equal "invalid value for attribute name: \"\\ba\\t\" can only include letters, numbers, dashes, and underscores", e.message
   end
 
   def test_validate_non_nil
diff --git test/rubygems/test_gem_text.rb test/rubygems/test_gem_text.rb
index a6e22e04da..04f3f605e8 100644
--- test/rubygems/test_gem_text.rb
+++ test/rubygems/test_gem_text.rb
@@ -36,6 +36,10 @@ def test_format_text_trailing # for two spaces after .
     assert_equal expected, format_text(text, 78)
   end
 
+  def test_format_removes_nonprintable_characters
+    assert_equal "text with weird .. stuff .", format_text("text with weird \x1b\x02 stuff \x7f", 40)
+  end
+
   def test_min3
     assert_equal 1, min3(1, 1, 1)
     assert_equal 1, min3(1, 1, 2)
@@ -74,4 +78,11 @@ def test_levenshtein_distance_replace
     assert_equal 7, levenshtein_distance("xxxxxxx", "ZenTest")
     assert_equal 7, levenshtein_distance("zentest", "xxxxxxx")
   end
+
+  def test_truncate_text
+    assert_equal "abc", truncate_text("abc", "desc")
+    assert_equal "Truncating desc to 2 characters:\nab", truncate_text("abc", "desc", 2)
+    s = "ab" * 500_001
+    assert_equal "Truncating desc to 1,000,000 characters:\n#{s[0, 1_000_000]}", truncate_text(s, "desc", 1_000_000)
+  end
 end