Buffer length underflow in LoginPacket causing unchecked exceptions to be thrown
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 team@pmmp.io
Affected software
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| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| Composer package | pocketmine/bedrock-protocol | < 8.0.2 | 8.0.2 |
References
- CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H- Weakness (CWE)
CWE-124- Platform
- Composer
- Package
pocketmine/bedrock-protocol- Disclosed
- 05.04.2022
- Updated
- 11.10.2026 10:22
Sources and licenses
OSV / GitHub Advisory Database - GHSA-5jfw-35xp-5m42 - CC BY 4.0
Vulnerability history: pocketmine/bedrock-protocol
All published vulnerabilities of this package (Composer package), newest first. Shows whether this is a one-off slip or a package that needs watching.
This is the only known vulnerability of this package.
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