Recently some of the Minecraft Server has found that the player using a modified mod to send the modified (unexpected) packet as 'ProjectRed' mod's packet to get any item they want without any permission.

For Example:
"The player could send the modified packet with any item they want inside to the server, at the server-side will directly set the contains item of the block without any check (e.g Barrel Block in ProjectRed - Exploration)."
https://github.com/MrTJP/ProjectRed/blob/dd27e1e3f194d3bef80e33b3f9372ce66891e715/src/mrtjp/projectred/exploration/TileBarrel.scala#L79

Please have looked to see if there's any method to solve this problem due to it will cause unauthorized code execution.
Thank you!