Remove '+' replacement from request cookies.

src/Microsoft.AspNetCore.Http/Internal/RequestCookieCollection.cs

@@ -79,8 +79,8 @@ public static RequestCookieCollection Parse(IList<string> values)
                 for (var i = 0; i < cookies.Count; i++)
                 {
                     var cookie = cookies[i];
-                    var name = Uri.UnescapeDataString(cookie.Name.Replace('+', ' '));
-                    var value = Uri.UnescapeDataString(cookie.Value.Replace('+', ' '));
+                    var name = Uri.UnescapeDataString(cookie.Name);
+                    var value = Uri.UnescapeDataString(cookie.Value);
                     store[name] = value;
                 }
 

test/Microsoft.AspNetCore.Http.Tests/RequestCookiesCollectionTests.cs

@@ -0,0 +1,46 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System.Linq;
+using Microsoft.AspNetCore.Http.Internal;
+using Microsoft.Extensions.Primitives;
+using Xunit;
+
+namespace Microsoft.AspNetCore.Http.Tests
+{
+    public class RequestCookiesCollectionTests
+    {
+        public static TheoryData UnEscapesKeyValues_Data
+        {
+            get
+            {
+                // key, value, expected
+                return new TheoryData<string, string, string>
+                {
+                    { "key=value", "key", "value" },
+                    { "key%2C=%21value", "key,", "!value" },
+                    { "ke%23y%2C=val%5Eue", "ke#y,", "val^ue" },
+                    { "key=value", "key", "value" },
+                    { "key%2C=%21value", "key,", "!value" },
+                    { "ke%23y%2C=val%5Eue", "ke#y,", "val^ue" },
+                    { "base64=QUI%2BREU%2FRw%3D%3D", "base64", "QUI+REU/Rw==" },
+                    { "base64=QUI+REU/Rw==", "base64", "QUI+REU/Rw==" },
+                };
+            }
+        }
+
+        [Theory]
+        [MemberData(nameof(UnEscapesKeyValues_Data))]
+        public void UnEscapesKeyValues(
+            string input,
+            string expectedKey,
+            string expectedValue)
+        {
+            var cookies = RequestCookieCollection.Parse(new StringValues(input));
+
+            Assert.Equal(1, cookies.Count);
+            Assert.Equal(expectedKey, cookies.Keys.Single());
+            Assert.Equal(expectedValue, cookies[expectedKey]);
+        }
+    }
+}

test/Microsoft.AspNetCore.Http.Tests/ResponseCookiesTest.cs

@@ -74,6 +74,7 @@ public static TheoryData EscapesKeyValuesBeforeSettingCookieData
                     { "key", "value", _builderPool, "key=value" },
                     { "key,", "!value", _builderPool, "key%2C=%21value" },
                     { "ke#y,", "val^ue", _builderPool, "ke%23y%2C=val%5Eue" },
+                    { "base64", "QUI+REU/Rw==", _builderPool, "base64=QUI%2BREU%2FRw%3D%3D" },
                 };
             }
         }