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GHSA-42qm-8v8m-m78c
No affected components available
Impact
A "mismatch" type InventoryTransactionPacket is sent by the client to request a resync of all currently open inventories.
Since PocketMine-MP does not rate-limit these "mismatch" transactions, and the syncing of inventories is not deferred until, e.g. the end of the current tick, they can be used as a very cheap bandwidth multiplier by making the server send out many MB of data (network serialized inventory items can be very large, especially when dealing with large amounts of NBT).
This is not currently known to have been exploited in the wild.
Patches
This problem was fixed in 4.18.0-ALPHA2 by ca6d51498f12427a947467da8fcad7811418e6cc alongside the introduction of the ItemStackRequest system implementation.
Workarounds
Plugins can handle DataPacketReceiveEvent for InventoryTransactionPacket and check if the type is MismatchTransactionData. If it is, apply some kind of rate limit (e.g. max 1 per tick).
The vulnerability can be exploited over the network without needing physical access. It is easy for an attacker to exploit this vulnerability. An attacker does not need any special privileges or access rights. No user interaction is needed for the attacker to exploit this vulnerability. The impact is confined to the system where the vulnerability exists. There is a low impact on the availability of the system.
Exploitation attempts have been detected. Elevated vigilance and prompt remediation are advised.
Probability that this vulnerability will be exploited in the wild within the next 30 days.
We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.
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