diff --git a/src/CalcManager/CalcManager.vcxproj b/src/CalcManager/CalcManager.vcxproj
index 462e97a9c3..7c31549282 100644
--- a/src/CalcManager/CalcManager.vcxproj
+++ b/src/CalcManager/CalcManager.vcxproj
@@ -131,6 +131,7 @@
       <PrecompiledHeader>Use</PrecompiledHeader>
       <CompileAsWinRT>false</CompileAsWinRT>
       <SDLCheck>true</SDLCheck>
+      <ControlFlowGuard>Guard</ControlFlowGuard>
       <AdditionalOptions>/Zm250 /std:c++20 /permissive- /Zc:twoPhase- /utf-8 /w44242 %(AdditionalOptions)</AdditionalOptions>
       <AdditionalIncludeDirectories>$(SolutionDir)..\src\;%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>
       <WarningLevel>Level4</WarningLevel>
@@ -167,6 +168,7 @@
       <PrecompiledHeader>Use</PrecompiledHeader>
       <CompileAsWinRT>false</CompileAsWinRT>
       <SDLCheck>true</SDLCheck>
+      <ControlFlowGuard>Guard</ControlFlowGuard>
       <AdditionalOptions>/Zm250 /std:c++20 /permissive- /Zc:twoPhase- /utf-8 /w44242 %(AdditionalOptions)</AdditionalOptions>
       <AdditionalIncludeDirectories>$(SolutionDir)..\src\;%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>
       <WarningLevel>Level4</WarningLevel>
@@ -202,6 +204,7 @@
       <PrecompiledHeader>Use</PrecompiledHeader>
       <CompileAsWinRT>false</CompileAsWinRT>
       <SDLCheck>true</SDLCheck>
+      <ControlFlowGuard>Guard</ControlFlowGuard>
       <AdditionalOptions>/Zm250 /std:c++20 /permissive- /Zc:twoPhase- /utf-8 /w44242 %(AdditionalOptions)</AdditionalOptions>
       <AdditionalIncludeDirectories>$(SolutionDir)..\src\;%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>
       <WarningLevel>Level4</WarningLevel>
diff --git a/src/CalcManager/Ratpack/conv.cpp b/src/CalcManager/Ratpack/conv.cpp
index 4f7609de09..27c745a90b 100644
--- a/src/CalcManager/Ratpack/conv.cpp
+++ b/src/CalcManager/Ratpack/conv.cpp
@@ -1500,34 +1500,30 @@ void numpowi32(_Inout_ PNUMBER* proot, int32_t power, uint32_t radix, int32_t pr
 void ratpowi32(_Inout_ PRAT* proot, int32_t power, int32_t precision)
 
 {
-    if (power < 0)
-    {
-        // Take the positive power and invert answer.
-        PNUMBER pnumtemp = nullptr;
-        ratpowi32(proot, -power, precision);
-        pnumtemp = (*proot)->pp;
-        (*proot)->pp = (*proot)->pq;
-        (*proot)->pq = pnumtemp;
-    }
-    else
-    {
-        PRAT lret = nullptr;
+    const bool invertResult = power < 0;
+    uint32_t magnitude =
+        invertResult ? static_cast<uint32_t>(-static_cast<int64_t>(power)) : static_cast<uint32_t>(power);
 
-        lret = i32torat(1);
+    PRAT lret = i32torat(1);
 
-        while (power > 0)
+    while (magnitude > 0)
+    {
+        if (magnitude & 1)
         {
-            if (power & 1)
-            {
-                mulnumx(&(lret->pp), (*proot)->pp);
-                mulnumx(&(lret->pq), (*proot)->pq);
-            }
-            mulrat(proot, *proot, precision);
-            trimit(&lret, precision);
-            trimit(proot, precision);
-            power >>= 1;
+            mulnumx(&(lret->pp), (*proot)->pp);
+            mulnumx(&(lret->pq), (*proot)->pq);
         }
-        destroyrat(*proot);
-        *proot = lret;
+        mulrat(proot, *proot, precision);
+        trimit(&lret, precision);
+        trimit(proot, precision);
+        magnitude >>= 1;
+    }
+    destroyrat(*proot);
+    *proot = lret;
+
+    if (invertResult)
+    {
+        // Invert after exponentiation so INT32_MIN never needs to be negated as an int32_t.
+        std::swap((*proot)->pp, (*proot)->pq);
     }
 }
diff --git a/src/Calculator.Tests/StandardCalculatorViewModelTests.cs b/src/Calculator.Tests/StandardCalculatorViewModelTests.cs
index 88c46ed245..4a3d570996 100644
--- a/src/Calculator.Tests/StandardCalculatorViewModelTests.cs
+++ b/src/Calculator.Tests/StandardCalculatorViewModelTests.cs
@@ -5,8 +5,10 @@
 using System.Collections.Generic;
 using System.Linq;
 using Microsoft.VisualStudio.TestTools.UnitTesting;
+using CalcManager.Interop;
 using CalculatorApp.ViewModel;
 using CalculatorApp.ViewModel.Common;
+using CalculatorApp.ViewModel.Snapshot;
 
 namespace Calculator.Tests
 {
@@ -152,6 +154,58 @@ private void ValidateViewModelValueAndSecondaryExpression(string value, string e
             }
         }
 
+        private void ValidateSnapshotReplayRejectsInvalidCommands(bool includeExpression)
+        {
+            int[] invalidCommands =
+            {
+                (int)CalculatorCommand.CommandEQU,
+                (int)CalculatorCommand.CommandCLEAR,
+                (int)CalculatorCommand.CommandCENTR,
+                (int)CalculatorCommand.CommandBACK,
+                (int)CalculatorCommand.CommandMCLEAR,
+                -1,
+                int.MaxValue
+            };
+
+            foreach (int invalidCommand in invalidCommands)
+            {
+                var snapshot = new StandardCalculatorSnapshot();
+                if (includeExpression)
+                {
+                    snapshot.ExpressionDisplay = new ExpressionDisplaySnapshot();
+                }
+                AppendSnapshotOperand(snapshot, (int)CalculatorCommand.Command1);
+                AppendSnapshotBinaryCommand(snapshot, invalidCommand);
+                AppendSnapshotOperand(snapshot, (int)CalculatorCommand.Command2);
+
+                _viewModel.Snapshot = snapshot;
+
+                ValidateViewModelValue("12");
+            }
+        }
+
+        private static void AppendSnapshotOperand(StandardCalculatorSnapshot snapshot, int command)
+        {
+            snapshot.DisplayCommands.Add(new ExpressionCommandWrapper(
+                CommandType.OperandCommand,
+                0,
+                new[] { command },
+                false,
+                false,
+                false));
+        }
+
+        private static void AppendSnapshotBinaryCommand(StandardCalculatorSnapshot snapshot, int command)
+        {
+            snapshot.DisplayCommands.Add(new ExpressionCommandWrapper(
+                CommandType.BinaryCommand,
+                command,
+                Array.Empty<int>(),
+                false,
+                false,
+                false));
+        }
+
         #endregion
 
         #region Constructor Tests
@@ -173,6 +227,56 @@ public void ViewModelConstructorButtonPressedInitializedTest()
             Assert.IsNotNull(vm.ButtonPressed);
         }
 
+        [TestMethod]
+        public void SnapshotReplayRejectsInvalidCommandsWithoutExpression()
+        {
+            ValidateSnapshotReplayRejectsInvalidCommands(false);
+        }
+
+        [TestMethod]
+        public void SnapshotReplayRejectsInvalidCommandsWithExpression()
+        {
+            ValidateSnapshotReplayRejectsInvalidCommands(true);
+        }
+
+        [TestMethod]
+        public void SnapshotReplayRejectsModeCommands()
+        {
+            int[] modeCommands =
+            {
+                (int)NumbersAndOperatorsEnum.Degree,
+                (int)NumbersAndOperatorsEnum.Radians,
+                (int)NumbersAndOperatorsEnum.Grads
+            };
+
+            foreach (int modeCommand in modeCommands)
+            {
+                var snapshot = new StandardCalculatorSnapshot();
+                AppendSnapshotBinaryCommand(snapshot, modeCommand);
+                AppendSnapshotOperand(snapshot, (int)CalculatorCommand.Command9);
+                AppendSnapshotOperand(snapshot, (int)CalculatorCommand.Command0);
+                AppendSnapshotBinaryCommand(snapshot, (int)CalculatorCommand.CommandSIN);
+
+                _viewModel.Snapshot = snapshot;
+
+                ValidateViewModelValue("1");
+            }
+        }
+
+        [TestMethod]
+        public void SnapshotReplayRejectsMemoryCommands()
+        {
+            var snapshot = new StandardCalculatorSnapshot();
+            AppendSnapshotOperand(snapshot, (int)CalculatorCommand.Command1);
+            AppendSnapshotBinaryCommand(snapshot, (int)CalculatorCommand.CommandMPLUS);
+            AppendSnapshotOperand(snapshot, (int)CalculatorCommand.Command2);
+
+            _viewModel.Snapshot = snapshot;
+
+            ValidateViewModelValue("12");
+            Assert.IsTrue(_viewModel.IsMemoryEmpty);
+        }
+
         #endregion
 
         #region Basic Arithmetic Tests
diff --git a/src/Calculator.ViewModels/StandardCalculatorViewModel.cs b/src/Calculator.ViewModels/StandardCalculatorViewModel.cs
index e715cfed77..2f5cba2ed2 100644
--- a/src/Calculator.ViewModels/StandardCalculatorViewModel.cs
+++ b/src/Calculator.ViewModels/StandardCalculatorViewModel.cs
@@ -708,10 +708,7 @@ public Snapshot.StandardCalculatorSnapshot Snapshot
                     {
                         // Expression was not evaluated before, or it was an error.
                         var displayCommands = GetCommandsFromExpressionCommands(snapshot.DisplayCommands);
-                        foreach (var cmd in displayCommands)
-                        {
-                            _standardCalculatorManager?.SendCommand((CalculatorCommand)cmd);
-                        }
+                        ReplaySnapshotCommands(displayCommands);
                         if (snapshot.PrimaryDisplay.IsError)
                         {
                             SetPrimaryDisplay(snapshot.PrimaryDisplay.DisplayValue, true);
@@ -727,10 +724,7 @@ public Snapshot.StandardCalculatorSnapshot Snapshot
                     else
                     {
                         var commands = GetCommandsFromExpressionCommands(snapshot.DisplayCommands);
-                        foreach (var cmd in commands)
-                        {
-                            _standardCalculatorManager?.SendCommand((CalculatorCommand)cmd);
-                        }
+                        ReplaySnapshotCommands(commands);
                     }
                 }
             }
@@ -2055,6 +2049,34 @@ private static List<int> GetCommandsFromExpressionCommands(IList<ExpressionComma
             return commands;
         }
 
+        private void ReplaySnapshotCommands(IEnumerable<int> commands)
+        {
+            foreach (int command in commands)
+            {
+                if (IsValidSnapshotReplayCommand(command))
+                {
+                    _standardCalculatorManager?.SendCommand((CalculatorCommand)command);
+                }
+            }
+        }
+
+        private static bool IsValidSnapshotReplayCommand(int command)
+        {
+            return (command >= (int)CalculatorCommand.Command0 && command <= (int)CalculatorCommand.CommandF)
+                || (command >= (int)CalculatorCommand.CommandAnd && command <= (int)CalculatorCommand.CommandPWR)
+                || (command >= (int)CalculatorCommand.CommandLogBaseY && command <= (int)CalculatorCommand.CommandNor)
+                || command == (int)CalculatorCommand.CommandRSHFL
+                || command == (int)CalculatorCommand.CommandSIGN
+                || command == (int)CalculatorCommand.CommandPNT
+                || (command >= (int)CalculatorCommand.CommandCHOP && command <= (int)CalculatorCommand.CommandPERCENT)
+                || command == (int)CalculatorCommand.CommandEXP
+                || command == (int)CalculatorCommand.CommandOPENP
+                || command == (int)CalculatorCommand.CommandCLOSEP
+                || (command >= (int)CalculatorCommand.CommandASIN && command <= (int)CalculatorCommand.CommandATANH)
+                || (command >= (int)CalculatorCommand.CommandSEC && command <= (int)CalculatorCommand.CommandRORC)
+                || command == (int)NumbersAndOperatorsEnum.Degrees;
+        }
+
     }
 
 }
diff --git a/src/CalculatorUITests/StandardModeFunctionalTests.cs b/src/CalculatorUITests/StandardModeFunctionalTests.cs
index ae23efa2f4..244a0d4dea 100644
--- a/src/CalculatorUITests/StandardModeFunctionalTests.cs
+++ b/src/CalculatorUITests/StandardModeFunctionalTests.cs
@@ -8,7 +8,14 @@
 using OpenQA.Selenium;
 
 using System;
+using System.Collections.Generic;
+using System.Diagnostics;
+using System.IO;
+using System.IO.Compression;
+using System.Text;
+using System.Text.Json;
 using System.Text.RegularExpressions;
+using System.Threading;
 
 namespace CalculatorUITests
 {
@@ -786,6 +793,90 @@ public void AoT_ErrorMessage_MessageRetentionUponExitingAoT()
 
         #endregion
 
+        #region Snapshot Protocol Tests
+
+        [TestMethod]
+        [DataRow(false)]
+        [DataRow(true)]
+        [Priority(0)]
+        public void SnapshotProtocolRejectsInjectedCommands(bool includeExpression)
+        {
+            var standardSnapshot = new Dictionary<string, object>
+            {
+                ["m"] = new Dictionary<string, object>(),
+                ["p"] = new Dictionary<string, object>
+                {
+                    ["d"] = "12",
+                    ["e"] = false,
+                },
+                ["c"] = new object[]
+                {
+                    BinaryCommand(322),
+                    OperandCommand(139),
+                    BinaryCommand(121),
+                    OperandCommand(130),
+                    BinaryCommand(102),
+                    BinaryCommand(int.MaxValue),
+                },
+            };
+            if (includeExpression)
+            {
+                standardSnapshot["e"] = new Dictionary<string, object>
+                {
+                    ["t"] = Array.Empty<object>(),
+                    ["c"] = Array.Empty<object>(),
+                };
+            }
+
+            var snapshot = new Dictionary<string, object>
+            {
+                ["m"] = 0,
+                ["s"] = standardSnapshot,
+            };
+            var json = JsonSerializer.Serialize(snapshot);
+            var uri = $"ms-calculator:snapshot/{Convert.ToBase64String(Compress(json))}";
+
+            Process.Start(new ProcessStartInfo(uri) { UseShellExecute = true });
+
+            Assert.IsTrue(
+                SpinWait.SpinUntil(() => page.CalculatorResults.GetCalculatorResultText() == "0", TimeSpan.FromSeconds(10)),
+                $"Snapshot replay produced '{page.CalculatorResults.GetCalculatorResultText()}' instead of rejecting the injected commands.");
+        }
+
+        private static Dictionary<string, object> BinaryCommand(int command)
+        {
+            return new Dictionary<string, object>
+            {
+                ["$t"] = 1,
+                ["c"] = command,
+            };
+        }
+
+        private static Dictionary<string, object> OperandCommand(int command)
+        {
+            return new Dictionary<string, object>
+            {
+                ["$t"] = 2,
+                ["n"] = false,
+                ["d"] = false,
+                ["s"] = false,
+                ["c"] = new[] { command },
+            };
+        }
+
+        private static byte[] Compress(string value)
+        {
+            using var compressed = new MemoryStream();
+            using (var stream = new DeflateStream(compressed, CompressionMode.Compress, true))
+            {
+                var bytes = Encoding.UTF8.GetBytes(value);
+                stream.Write(bytes, 0, bytes.Length);
+            }
+            return compressed.ToArray();
+        }
+
+        #endregion
+
         #region Error Tests
         /// <summary>
         /// These automated tests verify errors display gracefully
diff --git a/src/CalculatorUnitTests/RationalTest.cpp b/src/CalculatorUnitTests/RationalTest.cpp
index 7c8aebb6f0..486248b713 100644
--- a/src/CalculatorUnitTests/RationalTest.cpp
+++ b/src/CalculatorUnitTests/RationalTest.cpp
@@ -3,6 +3,7 @@
 
 #include "pch.h"
 #include <CppUnitTest.h>
+#include <limits>
 #include "Header Files/Rational.h"
 #include "Header Files/RationalMath.h"
 
@@ -40,6 +41,16 @@ TEST_METHOD(TestModuloOperandsNotModified)
     VERIFY_ARE_EQUAL(rat4, 4);
 }
 
+TEST_METHOD(TestInt32MinIntegerPower)
+{
+    PRAT base = Rational(-1).ToPRAT();
+    ratpowi32(&base, std::numeric_limits<int32_t>::min(), RATIONAL_PRECISION);
+    Rational result{ base };
+    destroyrat(base);
+
+    VERIFY_ARE_EQUAL(result, 1);
+}
+
 TEST_METHOD(TestModuloInteger)
 {
     // Check with integers