EMI v.1.1.10 and before, fixed in v.1.1.11, contains an Improper Validation of Specified Index, Position, or Offset in Input vulnerability. The specific issue is a failure to validate slot index and decrement stack count in EMI mod for Minecraft, which allows in-game item duplication.
https://gist.github.com/apple502j/6d691b62c37fc37b03b0784917064df6