Improperly checked metadata on tools/armour itemstacks received from the client

Impact

Due to a workaround applied in 1.13, an attacker may send a negative damage/meta value in a tool or armour item's NBT, which TypeConverter then blindly uses as if it was valid without being checked.

When this invalid metadata value reaches Durable->setDamage(), an exception is thrown because the metadata is not within the expected range for damage values.

This can be reproduced with either a too-large damage value, or a negative one.

Patches

c8e1cfcbee4945fd4b63d2a7e96025c59744d4f1

Workarounds

In theory this can be checked by plugins using a custom TypeConverter, but this is likely to be very cumbersome.

For more information

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