From 6a86f007f3924fbd2ea5eb222d9998da376ad0fc Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Micha=C5=82=20Janiszewski?=
 <janisozaur@users.noreply.github.com>
Date: Mon, 19 Sep 2016 20:25:00 +0200
Subject: [PATCH] Fix #4437: Crash in Network::Server_Handle_AUTH

---
 src/network/network.cpp | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/src/network/network.cpp b/src/network/network.cpp
index 0519248b7a..439ed3c513 100644
--- a/src/network/network.cpp
+++ b/src/network/network.cpp
@@ -670,7 +670,13 @@ uint8 Network::GetGroupIDByHash(const std::string &keyhash)
 
 	uint8 groupId = GetDefaultGroup();
 	if (networkUser != nullptr && networkUser->GroupId.HasValue()) {
-		groupId = networkUser->GroupId.GetValue();
+		const uint8 assignedGroup = networkUser->GroupId.GetValue();
+		if (GetGroupByID(assignedGroup) != nullptr) {
+			groupId = assignedGroup;
+		} else {
+			log_warning("User %s is assigned to non-existent group %u. Assigning to default group (%u)",
+						keyhash.c_str(), assignedGroup, groupId);
+		}
 	}
 	return groupId;
 }