GHSA-5jfw-35xp-5m42 Buffer length underflow in LoginPacket causing unchecked exceptions to be thrown

• Packagist pocketmine/bedrock-protocol: < 8.0.2 → fixed in 8.0.2

Impact `LoginPacket` uses `BinaryStream->getLInt()` to read the lengths of JSON payloads it wants to decode. Unfortunately, `BinaryStream->getLInt()` returns a signed integer, meaning that a malicious client can craft a packet with a large uint32 value for payload buffer size (which would be interpreted as a negative signed int32), causing `BinaryStream->get()` to throw an exception. In the context of PocketMine-MP, this leads to a server crash when the vulnerability is exploited. Patches e3fce7632b94e83fd6a518a87dcaf6a11681c4ac Workarounds This can be worked around by registering a custom `LoginPacket` implementation into `PacketPool` which overrides this code to patch it. For more information • Email us at [email protected]