From c4aae676b27ad0b4dd6488615d29883463847251 Mon Sep 17 00:00:00 2001
From: duckietm <troop@mailtjes.com>
Date: Tue, 2 Jun 2026 16:04:47 +0200
Subject: [PATCH] =?UTF-8?q?=F0=9F=86=99=20Security=20Fix?=
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Thanks to @Bop:

There's a group bug where you can accept anyone into a group within MS. There's no packet validation for accepting members if the group is invite only.
This is crucial because if you allow users to have rights who are group members, your rooms can be trashed. AKA YOUR EVENT ROOMS
---
 .../guilds/GuildAcceptMembershipEvent.java    | 84 +++++++++++--------
 1 file changed, 47 insertions(+), 37 deletions(-)

diff --git a/Emulator/src/main/java/com/eu/habbo/messages/incoming/guilds/GuildAcceptMembershipEvent.java b/Emulator/src/main/java/com/eu/habbo/messages/incoming/guilds/GuildAcceptMembershipEvent.java
index b4898da6..88f05e7e 100644
--- a/Emulator/src/main/java/com/eu/habbo/messages/incoming/guilds/GuildAcceptMembershipEvent.java
+++ b/Emulator/src/main/java/com/eu/habbo/messages/incoming/guilds/GuildAcceptMembershipEvent.java
@@ -25,45 +25,55 @@ public class GuildAcceptMembershipEvent extends MessageHandler {
         int userId = this.packet.readInt();
 
         Guild guild = Emulator.getGameEnvironment().getGuildManager().getGuild(guildId);
+
+        if (guild == null) {
+            return;
+        }
+
+        GuildMember actorMember = Emulator.getGameEnvironment().getGuildManager().getGuildMember(guild, this.client.getHabbo());
+        boolean canAccept = guild.getOwnerId() == this.client.getHabbo().getHabboInfo().getId()
+                || this.client.getHabbo().hasPermission(Permission.ACC_GUILD_ADMIN)
+                || (actorMember != null && (actorMember.getRank().equals(GuildRank.ADMIN) || actorMember.getRank().equals(GuildRank.OWNER)));
+
+        if (!canAccept) {
+            return;
+        }
+
+        GuildMember targetMember = Emulator.getGameEnvironment().getGuildManager().getGuildMember(guildId, userId);
+
+        if (targetMember == null) {
+            this.client.sendResponse(new GuildAcceptMemberErrorComposer(guild.getId(), GuildAcceptMemberErrorComposer.NO_LONGER_MEMBER));
+            return;
+        }
+
+        if (targetMember.getRank().type != GuildRank.REQUESTED.type) {
+            this.client.sendResponse(new GuildAcceptMemberErrorComposer(guild.getId(), GuildAcceptMemberErrorComposer.ALREADY_ACCEPTED));
+            return;
+        }
+
         Habbo habbo = Emulator.getGameEnvironment().getHabboManager().getHabbo(userId);
 
-        if (guild != null) {
-            GuildMember groupMember = Emulator.getGameEnvironment().getGuildManager().getGuildMember(guild, this.client.getHabbo());
-            if (guild.getOwnerId() == this.client.getHabbo().getHabboInfo().getId()
-                || this.client.getHabbo().hasPermission(Permission.ACC_GUILD_ADMIN)
-                || (groupMember != null && (groupMember.getRank().equals(GuildRank.ADMIN) || groupMember.getRank().equals(GuildRank.OWNER)))) {
-                if (habbo != null) {
-                    if (habbo.getHabboStats().hasGuild(guild.getId())) {
-                        this.client.sendResponse(new GuildAcceptMemberErrorComposer(guild.getId(), GuildAcceptMemberErrorComposer.ALREADY_ACCEPTED));
-                        return;
-                    } else {
-                        //Check the user has requested
-                        GuildMember member = Emulator.getGameEnvironment().getGuildManager().getGuildMember(guild, habbo);
-                        if (member == null || member.getRank().type != GuildRank.REQUESTED.type) {
-                            this.client.sendResponse(new GuildAcceptMemberErrorComposer(guild.getId(), GuildAcceptMemberErrorComposer.NO_LONGER_MEMBER));
-                            return;
-                        } else {
-                            GuildAcceptedMembershipEvent event = new GuildAcceptedMembershipEvent(guild, userId, habbo);
-                            Emulator.getPluginManager().fireEvent(event);
-                            if (!event.isCancelled()) {
-                                habbo.getHabboStats().addGuild(guild.getId());
-                                Emulator.getGameEnvironment().getGuildManager().joinGuild(guild, this.client, habbo.getHabboInfo().getId(), true);
-                                guild.decreaseRequestCount();
-                                guild.increaseMemberCount();
-                                this.client.sendResponse(new GuildRefreshMembersListComposer(guild));
-                                Room room = habbo.getHabboInfo().getCurrentRoom();
-                                if (room != null) {
-                                    if (room.getGuildId() == guildId) {
-                                        habbo.getClient().sendResponse(new GuildInfoComposer(guild, habbo.getClient(), false, Emulator.getGameEnvironment().getGuildManager().getGuildMember(guildId, userId)));
-                                        room.refreshRightsForHabbo(habbo);
-                                    }
-                                }
-                            }
-                        }
-                    }
-                } else {
-                    Emulator.getGameEnvironment().getGuildManager().joinGuild(guild, this.client, userId, true);
-                }
+        GuildAcceptedMembershipEvent event = new GuildAcceptedMembershipEvent(guild, userId, habbo);
+        Emulator.getPluginManager().fireEvent(event);
+
+        if (event.isCancelled()) {
+            return;
+        }
+
+        if (habbo != null) {
+            habbo.getHabboStats().addGuild(guild.getId());
+        }
+
+        Emulator.getGameEnvironment().getGuildManager().joinGuild(guild, this.client, userId, true);
+        guild.decreaseRequestCount();
+        guild.increaseMemberCount();
+        this.client.sendResponse(new GuildRefreshMembersListComposer(guild));
+
+        if (habbo != null) {
+            Room room = habbo.getHabboInfo().getCurrentRoom();
+            if (room != null && room.getGuildId() == guildId) {
+                habbo.getClient().sendResponse(new GuildInfoComposer(guild, habbo.getClient(), false, Emulator.getGameEnvironment().getGuildManager().getGuildMember(guildId, userId)));
+                room.refreshRightsForHabbo(habbo);
             }
         }
     }