diff --git a/Source/Core/Core/Slippi/SlippiNetplay.cpp b/Source/Core/Core/Slippi/SlippiNetplay.cpp
index 0329dd732d..5de524e298 100644
--- a/Source/Core/Core/Slippi/SlippiNetplay.cpp
+++ b/Source/Core/Core/Slippi/SlippiNetplay.cpp
@@ -388,18 +388,26 @@ unsigned int SlippiNetplayClient::OnData(sf::Packet& packet, ENetPeer* peer)
   case NetPlay::NP_MSG_SLIPPI_MATCH_SELECTIONS:
   {
     auto s = readSelectionsFromPacket(packet);
-    INFO_LOG_FMT(SLIPPI_ONLINE, "[Netplay] Received selections from opponent with player idx {}",
-                 s->playerIdx);
-    u8 idx = PlayerIdxFromPort(s->playerIdx);
-    matchInfo.remotePlayerSelections[idx].Merge(*s);
+    if (!s->error)
+    {
+      INFO_LOG_FMT(SLIPPI_ONLINE, "[Netplay] Received selections from opponent with player idx {}",
+                   s->playerIdx);
+      u8 idx = PlayerIdxFromPort(s->playerIdx);
+      if (idx >= m_remotePlayerCount)
+      {
+        ERROR_LOG_FMT(SLIPPI_ONLINE, "Got match selection packet with invalid player idx {}", idx);
+        break;
+      }
+      matchInfo.remotePlayerSelections[idx].Merge(*s);
 
-    // This might be a good place to reset some logic? Game can't start until we receive this msg
-    // so this should ensure that everything is initialized before the game starts
-    hasGameStarted = false;
+      // This might be a good place to reset some logic? Game can't start until we receive this msg
+      // so this should ensure that everything is initialized before the game starts
+      hasGameStarted = false;
 
-    // Reset remote pad queue such that next inputs that we get are not compared to inputs from last
-    // game
-    remotePadQueue[idx].clear();
+      // Reset remote pad queue such that next inputs that we get are not compared to inputs from
+      // last game
+      remotePadQueue[idx].clear();
+    }
   }
   break;
 
@@ -418,8 +426,11 @@ unsigned int SlippiNetplayClient::OnData(sf::Packet& packet, ENetPeer* peer)
       remoteSentChatMessageId = 0;
       break;
     }
-    // set message id to netplay instance
-    remoteChatMessageSelection = std::move(playerSelection);
+    if (!playerSelection->error)
+    {
+      // set message id to netplay instance
+      remoteChatMessageSelection = std::move(playerSelection);
+    }
   }
   break;
 
@@ -461,8 +472,49 @@ SlippiNetplayClient::ReadChatMessageFromPacket(sf::Packet& packet)
 {
   auto s = std::make_unique<SlippiPlayerSelections>();
 
-  packet >> s->messageId;
-  packet >> s->playerIdx;
+  if (!(packet >> s->messageId))
+  {
+    ERROR_LOG(SLIPPI_ONLINE, "Chat packet too small to read message ID");
+    s->error = true;
+    return std::move(s);
+  }
+  if (!(packet >> s->playerIdx))
+  {
+    ERROR_LOG(SLIPPI_ONLINE, "Chat packet too small to read player index");
+    s->error = true;
+    return std::move(s);
+  }
+
+  switch (s->messageId)
+  {
+  // Only these 16 message IDs are allowed
+  case 136:
+  case 129:
+  case 130:
+  case 132:
+  case 34:
+  case 40:
+  case 33:
+  case 36:
+  case 72:
+  case 66:
+  case 68:
+  case 65:
+  case 24:
+  case 18:
+  case 20:
+  case 17:
+  {
+    // Good message ID. Do nothing
+    break;
+  }
+  default:
+  {
+    ERROR_LOG_FMT(SLIPPI_ONLINE, "Received invalid chat message index: {}", s->messageId);
+    s->error = true;
+    break;
+  }
+  }
 
   return std::move(s);
 }
@@ -472,17 +524,46 @@ SlippiNetplayClient::readSelectionsFromPacket(sf::Packet& packet)
 {
   auto s = std::make_unique<SlippiPlayerSelections>();
 
-  packet >> s->characterId;
-  packet >> s->characterColor;
-  packet >> s->isCharacterSelected;
-
-  packet >> s->playerIdx;
-
-  packet >> s->stageId;
-  packet >> s->isStageSelected;
-  packet >> s->rngOffset;
-
-  packet >> s->teamId;
+  if (!(packet >> s->characterId))
+  {
+    ERROR_LOG(SLIPPI_ONLINE, "Received invalid player selection");
+    s->error = true;
+  }
+  if (!(packet >> s->characterColor))
+  {
+    ERROR_LOG(SLIPPI_ONLINE, "Received invalid player selection");
+    s->error = true;
+  }
+  if (!(packet >> s->isCharacterSelected))
+  {
+    ERROR_LOG(SLIPPI_ONLINE, "Received invalid player selection");
+    s->error = true;
+  }
+  if (!(packet >> s->playerIdx))
+  {
+    ERROR_LOG(SLIPPI_ONLINE, "Received invalid player selection");
+    s->error = true;
+  }
+  if (!(packet >> s->stageId))
+  {
+    ERROR_LOG(SLIPPI_ONLINE, "Received invalid player selection");
+    s->error = true;
+  }
+  if (!(packet >> s->isStageSelected))
+  {
+    ERROR_LOG(SLIPPI_ONLINE, "Received invalid player selection");
+    s->error = true;
+  }
+  if (!(packet >> s->rngOffset))
+  {
+    ERROR_LOG(SLIPPI_ONLINE, "Received invalid player selection");
+    s->error = true;
+  }
+  if (!(packet >> s->teamId))
+  {
+    ERROR_LOG(SLIPPI_ONLINE, "Received invalid player selection");
+    s->error = true;
+  }
 
   return std::move(s);
 }
diff --git a/Source/Core/Core/Slippi/SlippiNetplay.h b/Source/Core/Core/Slippi/SlippiNetplay.h
index f197d50df3..445b649bb5 100644
--- a/Source/Core/Core/Slippi/SlippiNetplay.h
+++ b/Source/Core/Core/Slippi/SlippiNetplay.h
@@ -54,7 +54,8 @@ public:
 
   u32 rngOffset{};
 
-  int messageId{};
+  int messageId = 0;
+  bool error = false;
 
   void Merge(SlippiPlayerSelections& s)
   {