CVE-2017-0902

@@ -110,7 +110,7 @@ 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
 

@@ -241,6 +241,21 @@ 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"