diff --git a/src/libraries/System.Net.Requests/src/Resources/Strings.resx b/src/libraries/System.Net.Requests/src/Resources/Strings.resx
index e746e70fefa499..4919a50fbaa0a8 100644
--- a/src/libraries/System.Net.Requests/src/Resources/Strings.resx
+++ b/src/libraries/System.Net.Requests/src/Resources/Strings.resx
@@ -196,7 +196,7 @@
     <value>The underlying connection was closed: An unexpected error occurred on a receive</value>
   </data>
   <data name="net_ftp_no_newlines" xml:space="preserve">
-    <value>CRLF character pair is not allowed in FtpWebRequest inputs.</value>
+    <value>CR and LF characters are not allowed in FtpWebRequest inputs.</value>
   </data>
   <data name="net_webstatus_NameResolutionFailure" xml:space="preserve">
     <value>The remote name could not be resolved</value>
diff --git a/src/libraries/System.Net.Requests/src/System/Net/FtpControlStream.cs b/src/libraries/System.Net.Requests/src/System/Net/FtpControlStream.cs
index ba72c6f8a9dc76..6673d8483ec158 100644
--- a/src/libraries/System.Net.Requests/src/System/Net/FtpControlStream.cs
+++ b/src/libraries/System.Net.Requests/src/System/Net/FtpControlStream.cs
@@ -1147,7 +1147,7 @@ private string GetPortCommandLine()
         /// </summary>
         private static string FormatFtpCommand(string command, string? parameter)
         {
-            if (parameter is not null && parameter.Contains("\r\n", StringComparison.Ordinal))
+            if (parameter is not null && parameter.AsSpan().ContainsAny('\r', '\n'))
             {
                 throw new FormatException(SR.net_ftp_no_newlines);
             }
diff --git a/src/libraries/System.Net.Requests/src/System/Net/FtpWebRequest.cs b/src/libraries/System.Net.Requests/src/System/Net/FtpWebRequest.cs
index f470879e993e41..91b95a5eea6604 100644
--- a/src/libraries/System.Net.Requests/src/System/Net/FtpWebRequest.cs
+++ b/src/libraries/System.Net.Requests/src/System/Net/FtpWebRequest.cs
@@ -487,7 +487,9 @@ internal FtpWebRequest(Uri uri)
             if ((object)uri.Scheme != (object)Uri.UriSchemeFtp)
                 throw new ArgumentOutOfRangeException(nameof(uri));
 
-            if (uri.OriginalString.Contains("\r\n", StringComparison.Ordinal))
+            if (uri.OriginalString.AsSpan().ContainsAny('\r', '\n') ||
+                uri.OriginalString.Contains("%0A", StringComparison.OrdinalIgnoreCase) ||
+                uri.OriginalString.Contains("%0D", StringComparison.OrdinalIgnoreCase))
                 throw new FormatException(SR.net_ftp_no_newlines);
 
             _timerCallback = new TimerThread.Callback(TimerCallback);
diff --git a/src/libraries/System.Net.Requests/tests/FtpWebRequestTest.cs b/src/libraries/System.Net.Requests/tests/FtpWebRequestTest.cs
index 5401b1e93ebbb7..aae99260d14301 100644
--- a/src/libraries/System.Net.Requests/tests/FtpWebRequestTest.cs
+++ b/src/libraries/System.Net.Requests/tests/FtpWebRequestTest.cs
@@ -29,6 +29,23 @@ public FtpExecutionMode(bool useSsl, bool usePassive, bool useAsync, bool useOld
             }
         }
 
+        [Theory]
+        [InlineData("ftp://foo.com/bar\r\nbaz")]
+        [InlineData("ftp://foo.com/bar\rbaz")]
+        [InlineData("ftp://foo.com/bar\nbaz")]
+        [InlineData("ftp://foo.com/bar%0D%0Abaz")]
+        [InlineData("ftp://foo.com/bar%0d%0abaz")]
+        [InlineData("ftp://foo.com/bar%0D%0abaz")]
+        [InlineData("ftp://foo.com/bar%0Dbaz")]
+        [InlineData("ftp://foo.com/bar%0dbaz")]
+        [InlineData("ftp://foo.com/bar%0Abaz")]
+        [InlineData("ftp://foo.com/bar%0abaz")]
+        public void Ctor_NewLineInUri_ThrowsFormatException(string uriString)
+        {
+            Uri uri = new Uri(uriString, UriKind.Absolute);
+            Assert.Throws<FormatException>(() => WebRequest.Create(uri));
+        }
+
         [Fact]
         public void Ctor_VerifyDefaults_Success()
         {
@@ -211,12 +228,15 @@ public void Ftp_Ignore_NewLine_Constructor_Throws_FormatException()
             Assert.Throws<FormatException>(() => WebRequest.Create($"{uri}\r\n{WebRequestMethods.Ftp.AppendFile} {Guid.NewGuid().ToString()}"));
         }
 
-        [ConditionalFact(typeof(FtpWebRequestTest), nameof(LocalServerAvailable))]
-        public void Ftp_Ignore_NewLine_GetRequestStream_And_GetResponse_Throws_FormatException_As_InnerException()
+        [ConditionalTheory(typeof(FtpWebRequestTest), nameof(LocalServerAvailable))]
+        [InlineData("test\r\ntest2")]
+        [InlineData("test\rtest2")]
+        [InlineData("test\ntest2")]
+        public void Ftp_Ignore_NewLine_GetRequestStream_And_GetResponse_Throws_FormatException_As_InnerException(string credential)
         {
             FtpWebRequest ftpWebRequest = (FtpWebRequest)WebRequest.Create(absoluteUri + Guid.NewGuid().ToString());
             ftpWebRequest.Method = "APPE";
-            ftpWebRequest.Credentials = new NetworkCredential("test\r\ntest2", "test\r\ntest2");
+            ftpWebRequest.Credentials = new NetworkCredential(credential, credential);
             var requestException = Assert.Throws<WebException>(() => ftpWebRequest.GetRequestStream());
             Assert.True(requestException.InnerException is FormatException);
 
@@ -224,6 +244,20 @@ public void Ftp_Ignore_NewLine_GetRequestStream_And_GetResponse_Throws_FormatExc
             Assert.True(responseException.InnerException is FormatException);
         }
 
+        [ConditionalTheory(typeof(FtpWebRequestTest), nameof(LocalServerAvailable))]
+        [InlineData("ok\r\nbad")]
+        [InlineData("ok\rbad")]
+        [InlineData("ok\nbad")]
+        public void Ftp_NewLineInRenameTo_GetResponse_Throws_FormatException_As_InnerException(string renameTo)
+        {
+            FtpWebRequest request = (FtpWebRequest)WebRequest.Create(absoluteUri + Guid.NewGuid().ToString());
+            request.Method = WebRequestMethods.Ftp.Rename;
+            request.RenameTo = renameTo;
+
+            WebException ex = Assert.Throws<WebException>(() => request.GetResponse());
+            Assert.IsType<FormatException>(ex.InnerException);
+        }
+
         private static async Task<MemoryStream> DoAsync(FtpWebRequest request, MemoryStream requestBody)
         {
             if (requestBody != null)