Impact
An attacker could crash PocketMine-MP by sending malformed JSON in LoginPacket.
This happened due to the particular handling of NULL types in the json mapper which accepts NULL type values in typed arrays which PocketMine-MP did not expect.
Code processing arrays in the JSON data could then crash due to unexpected NULL elements.
Patches
This problem was fixed in 5.3.1 and 4.23.1 by updating JsonMapper to include the following commit: pmmp/netresearch-jsonmapper@4f90e8d
An upstream patch for this issue was proposed via cweiske/jsonmapper#211; however, as of 2024-05-15, the patch has not been accepted upstream due to debate about how to deal with the behavior. For now, a fork of JsonMapper is used by PocketMine-MP to workaround the issue.
Workarounds
A plugin may handle DataPacketReceiveEvent for LoginPacket and check that none of the input arrays contain NULL where it's not expected, but this is rather cumbersome.
References
Proposed upstream patch for a behavior change: cweiske/jsonmapper#211
References
Impact
An attacker could crash PocketMine-MP by sending malformed JSON in
LoginPacket.This happened due to the particular handling of NULL types in the json mapper which accepts NULL type values in typed arrays which PocketMine-MP did not expect.
Code processing arrays in the JSON data could then crash due to unexpected
NULLelements.Patches
This problem was fixed in 5.3.1 and 4.23.1 by updating JsonMapper to include the following commit: pmmp/netresearch-jsonmapper@4f90e8d
An upstream patch for this issue was proposed via cweiske/jsonmapper#211; however, as of 2024-05-15, the patch has not been accepted upstream due to debate about how to deal with the behavior. For now, a fork of JsonMapper is used by PocketMine-MP to workaround the issue.
Workarounds
A plugin may handle
DataPacketReceiveEventforLoginPacketand check that none of the input arrays containNULLwhere it's not expected, but this is rather cumbersome.References
Proposed upstream patch for a behavior change: cweiske/jsonmapper#211
References