From 2d4fd05adf6d675704371f4539a31af5260c0f4e Mon Sep 17 00:00:00 2001
From: James Newton-King <james@newtonking.com>
Date: Sat, 27 Jul 2019 15:39:25 +1200
Subject: [PATCH] Add host caution to MVC GetUri extension methods (#12629)

---
 .../Routing/ControllerLinkGeneratorExtensions.cs | 16 ++++++++++++++++
 .../src/Routing/PageLinkGeneratorExtensions.cs   | 16 ++++++++++++++++
 2 files changed, 32 insertions(+)

diff --git a/src/Mvc/Mvc.Core/src/Routing/ControllerLinkGeneratorExtensions.cs b/src/Mvc/Mvc.Core/src/Routing/ControllerLinkGeneratorExtensions.cs
index fb02fae6f4..d15eaef020 100644
--- a/src/Mvc/Mvc.Core/src/Routing/ControllerLinkGeneratorExtensions.cs
+++ b/src/Mvc/Mvc.Core/src/Routing/ControllerLinkGeneratorExtensions.cs
@@ -138,6 +138,14 @@ namespace Microsoft.AspNetCore.Routing
         /// names from <c>RouteOptions</c>.
         /// </param>
         /// <returns>A absolute URI, or <c>null</c> if a URI cannot be created.</returns>
+        /// <remarks>
+        /// <para>
+        /// The value of <paramref name="host" /> should be a trusted value. Relying on the value of the current request
+        /// can allow untrusted input to influence the resulting URI unless the <c>Host</c> header has been validated.
+        /// See the deployment documentation for instructions on how to properly validate the <c>Host</c> header in
+        /// your deployment environment.
+        /// </para>
+        /// </remarks>
         public static string GetUriByAction(
             this LinkGenerator generator,
             HttpContext httpContext,
@@ -189,6 +197,14 @@ namespace Microsoft.AspNetCore.Routing
         /// names from <c>RouteOptions</c>.
         /// </param>
         /// <returns>A absolute URI, or <c>null</c> if a URI cannot be created.</returns>
+        /// <remarks>
+        /// <para>
+        /// The value of <paramref name="host" /> should be a trusted value. Relying on the value of the current request
+        /// can allow untrusted input to influence the resulting URI unless the <c>Host</c> header has been validated.
+        /// See the deployment documentation for instructions on how to properly validate the <c>Host</c> header in
+        /// your deployment environment.
+        /// </para>
+        /// </remarks>
         public static string GetUriByAction(
             this LinkGenerator generator,
             string action,
diff --git a/src/Mvc/Mvc.Core/src/Routing/PageLinkGeneratorExtensions.cs b/src/Mvc/Mvc.Core/src/Routing/PageLinkGeneratorExtensions.cs
index 032831560b..f1725f2fe0 100644
--- a/src/Mvc/Mvc.Core/src/Routing/PageLinkGeneratorExtensions.cs
+++ b/src/Mvc/Mvc.Core/src/Routing/PageLinkGeneratorExtensions.cs
@@ -135,6 +135,14 @@ namespace Microsoft.AspNetCore.Routing
         /// names from <c>RouteOptions</c>.
         /// </param>
         /// <returns>A absolute URI, or <c>null</c> if a URI cannot be created.</returns>
+        /// <remarks>
+        /// <para>
+        /// The value of <paramref name="host" /> should be a trusted value. Relying on the value of the current request
+        /// can allow untrusted input to influence the resulting URI unless the <c>Host</c> header has been validated.
+        /// See the deployment documentation for instructions on how to properly validate the <c>Host</c> header in
+        /// your deployment environment.
+        /// </para>
+        /// </remarks>
         public static string GetUriByPage(
             this LinkGenerator generator,
             HttpContext httpContext,
@@ -186,6 +194,14 @@ namespace Microsoft.AspNetCore.Routing
         /// names from <c>RouteOptions</c>.
         /// </param>
         /// <returns>A absolute URI, or <c>null</c> if a URI cannot be created.</returns>
+        /// <remarks>
+        /// <para>
+        /// The value of <paramref name="host" /> should be a trusted value. Relying on the value of the current request
+        /// can allow untrusted input to influence the resulting URI unless the <c>Host</c> header has been validated.
+        /// See the deployment documentation for instructions on how to properly validate the <c>Host</c> header in
+        /// your deployment environment.
+        /// </para>
+        /// </remarks>
         public static string GetUriByPage(
             this LinkGenerator generator,
             string page,