NaN/INF in serverbound movement packets can crash clients and servers
Impact
A malicious client may send a MovePlayerPacket to the server whose position or rotation contains NaN or INF. Since neither the server nor vanilla client handles this properly, a number of interesting side effects come into play.
Source excerpt · OSVAffected packages
Start with the recorded fix for your release branch. Check your installed version and test compatibility before upgrading. Fixing this advisory does not rule out other vulnerabilities in the release.
| Affected range | Recorded fix |
|---|---|
| Earlier releases before 3.18.1Ecosystem versions | 3.18.1 |
Version evidence: OSV · GHSA-fm35-jgg3-3grx
View original version evidence (120 explicit versions)
Original source description
Impact
A malicious client may send a MovePlayerPacket to the server whose position or rotation contains NaN or INF. Since neither the server nor vanilla client handles this properly, a number of interesting side effects come into play.
- The server may crash in various ways if this exploit is used, because some mathematical operations on NaN/INF generate PHP warnings, which are converted into exceptions.
- Clients may not be able to see other clients who have a NaN/INF rotation.
- Clients may also crash in such cases.
Patches
A patch for this was included in the 3.18.1 release: https://github.com/pmmp/PocketMine-MP/commit/fb20bb38327b4c08ee3976640cd0dd547388a638
Workarounds
Workarounds could be implemented as plugins using DataPacketReceiveEvent to block any inbound movement packets containing bogus values.
For more information
If you have any questions or comments about this advisory:
- Open an issue in pmmp/PocketMine-MP
- Email us at team@pmmp.io