2 files changed, 13 insertions, 0 deletions
diff --git a/src/server/game/AI/SmartScripts/SmartScript.cpp b/src/server/game/AI/SmartScripts/SmartScript.cpp
index bd51fe0a85b..49beb0ae86f 100644
--- a/src/server/game/AI/SmartScripts/SmartScript.cpp
+++ b/src/server/game/AI/SmartScripts/SmartScript.cpp
@@ -76,6 +76,7 @@ SmartScript::SmartScript()
     goOrigGUID = 0;
     mLastInvoker = 0;
     mScriptType = SMART_SCRIPT_TYPE_CREATURE;
+    isProcessingTimedActionList = false;
 }
 
 SmartScript::~SmartScript()
@@ -3253,6 +3254,7 @@ void SmartScript::OnUpdate(uint32 const diff)
     bool needCleanup = true;
     if (!mTimedActionList.empty())
     {
+        isProcessingTimedActionList = true;
         for (SmartAIEventList::iterator i = mTimedActionList.begin(); i != mTimedActionList.end(); ++i)
         {
             if ((*i).enableTimed)
@@ -3261,6 +3263,8 @@ void SmartScript::OnUpdate(uint32 const diff)
                 needCleanup = false;
             }
         }
+
+        isProcessingTimedActionList = false;
     }
     if (needCleanup)
         mTimedActionList.clear();
@@ -3502,6 +3506,14 @@ Unit* SmartScript::DoFindClosestFriendlyInRange(float range, bool playerOnly)
 
 void SmartScript::SetScript9(SmartScriptHolder& e, uint32 entry)
 {
+    //do NOT clear mTimedActionList if it's being iterated because it will invalidate the iterator and delete
+    // any SmartScriptHolder contained like the "e" parameter passed to this function
+    if (isProcessingTimedActionList)
+    {
+        TC_LOG_ERROR("scripts.ai", "Entry %d SourceType %u Event %u Action %u is trying to overwrite timed action list from a timed action, this is not allowed!.", e.entryOrGuid, e.GetScriptType(), e.GetEventType(), e.GetActionType());
+        return;
+    }
+
     mTimedActionList.clear();
     mTimedActionList = sSmartScriptMgr->GetScript(entry, SMART_SCRIPT_TYPE_TIMED_ACTIONLIST);
     if (mTimedActionList.empty())
diff --git a/src/server/game/AI/SmartScripts/SmartScript.h b/src/server/game/AI/SmartScripts/SmartScript.h
index 2e1068d1bff..861da6d86d2 100644
--- a/src/server/game/AI/SmartScripts/SmartScript.h
+++ b/src/server/game/AI/SmartScripts/SmartScript.h
@@ -222,6 +222,7 @@ class SmartScript
         SmartAIEventList mEvents;
         SmartAIEventList mInstallEvents;
         SmartAIEventList mTimedActionList;
+        bool isProcessingTimedActionList;
         Creature* me;
         uint64 meOrigGUID;
         GameObject* go;