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GHSA-fqx3-r75h-vc89
No affected components available
Impact
Due to a workaround for unmapped network items implemented in 4.0.0-BETA5 (8ac16345a3bc099b62c1f5cfbf3b736e621c3f76), arbitrary item IDs are able to be written into an item's NBT. The intended purpose of this is to make said unmapped network items able to be moved around the inventory without issues.
This led to an exploit due to internal limits on the range that item IDs can occupy (-32768 - 32767), while the tag type used to represent the replacement IDs for unknown items is a TAG_Int, allowing a range from -(2^31) - 2^31 - 1. This leads to an uncaught exception which crashes the server.
Patches
5fd685e07d61ef670584ed11a52fd5f4b99a81a7
Workarounds
In theory this can be checked by plugins using a custom TypeConverter, but this is likely to be very cumbersome.
For more information
If you have any questions or comments about this advisory:
- Email us at team@pmmp.io
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 high 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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