From 2b636adc2f014c53720d4a578b0eb28dbdacb8f7 Mon Sep 17 00:00:00 2001
From: Benjamin Jackson <38561765+heyitsbench@users.noreply.github.com>
Date: Sun, 28 Jul 2024 15:40:21 -0400
Subject: [PATCH] fix(Core/AchievementMgr): Check for null achievement before
 being derefenced. (#19504)

* Init.

* Reviewed changes.
---
 src/server/game/Achievements/AchievementMgr.cpp | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/src/server/game/Achievements/AchievementMgr.cpp b/src/server/game/Achievements/AchievementMgr.cpp
index 13072d3c2..37ed221ee 100644
--- a/src/server/game/Achievements/AchievementMgr.cpp
+++ b/src/server/game/Achievements/AchievementMgr.cpp
@@ -2473,10 +2473,15 @@ bool AchievementGlobalMgr::IsStatisticAchievement(AchievementEntry const* achiev
 
 bool AchievementGlobalMgr::IsAverageCriteria(AchievementCriteriaEntry const* criteria) const
 {
-    if ((sAchievementStore.LookupEntry(criteria->referredAchievement))->flags & ACHIEVEMENT_FLAG_AVERAGE)
+    auto referencedAchievement = sAchievementStore.LookupEntry(criteria->referredAchievement);
+
+    if (!referencedAchievement)
+        return false;
+
+    if (referencedAchievement->flags & ACHIEVEMENT_FLAG_AVERAGE)
         return true;
 
-    if (AchievementEntryList const* achRefList = GetAchievementByReferencedId(criteria->referredAchievement))
+    if (AchievementEntryList const* achRefList = GetAchievementByReferencedId(referencedAchievement->ID))
         for (AchievementEntryList::const_iterator itr = achRefList->begin(); itr != achRefList->end(); ++itr)
             if ((*itr)->flags & ACHIEVEMENT_FLAG_AVERAGE)
                 return true;