So I'm publishing a list of bugs with more or less comprehensive information, including measures that need to be taken to exclude these.
Here's a video demonstration (with version 3.46) and a description of each bug pictured in video:
|Effect||Item duplication (appliable to any item, x2 at time)|
|Detection||No visible effect (also logging plugins will not display item copies being taken from chest), apart from people normally being simple enough to store stacks of duplicated items in same chest.|
|Explanation||This is a long-lasting Bukkit bug, related to accessing container interfaces via API call (plugins). If the chunk gets unloaded while you are doing this, container will continue existing (java memory handling, you see) until UI screen drops the reference to it. Chest contents (in chunk) are not synced with this "floating" chest though.|
and change line saying
To note, it's pretty suprising, how many servers still have this available, despite of this bug being reported on every second ChestShop discussion page on Bukkit plugin directory.
|Notes||It is also possible to do this with non-delayed teleportation by either having macros key mod, or any other means to send a chat packet while chest UI is open.|
|Effect||Possibility to create any amount of funds "out of thin air".|
|Detection||Clearly visible in server log as a normal ChestShop transaction message. Can be traced back to "source" user with simple text search. As well easily seen on sign, by strange third line contents.|
|Explanation||Undefined. There's a suspect of some very sloppy coding in either ChestShop or commonly used economy plugins.|
|Fixing||Ability to set negative item prices is fixed as of 3.50t49|
|Effect||Item duplication upon purchasing. Shop never runs out of stock.|
|Detection||Renamed / enchanced items in one or more ChestShops - commonly only few items are put in, as there is no need for larger quantities.|
Also can be seen in server log as purchase of too many items from the same shop.
|Explanation||In short, this is just an item comparison bug.|
|Fixing||Development versions of ChestShop larger than 3.46 kind of fix this, by not allowing to sell enchanted items at all. Doesn't look like a persistent solution.|
|Notes||Fun fact: I've found this bug while trying to do a small prank, by making a shop that sold renamed items, e.g. "Diamond" items renamed to "Coal" and other. Later it was spotted, that shops are at full stock, despite of people purchasing items periodically.|
|Air is free|
|Effect||Allows users to sell zero quantities of items.|
|Detection||If shop sells 0 items at once, a "ghostly" item stack will be created in player's inventory. Since item stack is zero size, it will disappear as soon as any operation is done about it (e.g. trying to drag it in inventory, drop, etc.)|
Some of items (such as potions, experience bottles, and mob eggs) can be still used while at zero quantity though, making this fairly exploitable.
|Replication||Create a ChestShop with item quantity stated as 0|
|Explanation||Simple enough, of course there's enough items in chest to subtract no items from those.|
|Fixing||Ability to sell zero items is fixed as of 3.50t49|
|Notes||You can "sell" even items that you do not have.|
This is also the only way to sell air (nothing) in a shop.