Bug #556

Critical Server-Side Crash and Local Network Saturation Due to Physics Replication Desync

Status:	Open
Priority:	Critical
Added by:	Anonymous on June 18, '26
Assigned to:	Unassigned
Due date:
Reported for:	1.23.0. Town Hall Revamp Auto
Roblox Id:	3842102402

Steps to Reproduce

1. Launch a dedicated private or public server instance of Welcome to Bloxburg.
2. Ensure you have a 'Classic Beach Ball' asset spawned inside or right next to a swimming pool.
3. Walk or jump with your avatar directly into the tight gap where the spherical geometry of the beach ball clips against the collision box of the swimming pool's edge/wall.
4. Jam the character model continuously into this intersection to force the physics engine to overlap the three variables (Avatar, Ball, Water Volume).
5. The physics engine will fail the calculation loop, instantly flooding the network interface card with high-frequency corrupted data, causing the local home router to freeze up due to packet saturation, followed by a complete hardware lockup of the operating system (unresponsive to Ctrl+Alt+Del) and a total crash of the Roblox server instance.

Explanation

Server-Side Instance Crash (DoS) and Local Network Saturation via Physics Replication Desync

A critical vulnerability has been identified in the physics replication layer of the Welcome to Bloxburg game instances. The flaw allows a client to trigger an unhandled mathematical conflict within the server's physics engine thread, leading to a complete Server-Side Denial of Service (DoS) and an immediate local infrastructure network saturation.

The issue stems from a severe desynchronization during collision resolution. When a player's character asset forces a simultaneous collision boundary between a network-replicated spherical object (such as the Classic Beach Ball) and a fluid container bounding box (the swimming pool geometry), the Roblox Inertial Physics Engine fails to compute the appropriate buoyancy and positional displacement vectors.

Consequently, the engine applies an exponential force calculation in an attempt to separate the clipping assets, accelerating the character model to infinite velocity coordinates (V -> inf).

Before the local client process crashes due to a GPU rendering pipeline cache overflow, the network layer attempts to replicate these invalid floating-point coordinates upstream. This transmits an unmanageable broadcast storm of thousands of corrupted physics packets per second. This influx completely saturates the local network router's buffer (inducing a local network Denial of Service/Bufferbloat that drops internet connectivity for the entire household) immediately followed by a total OS kernel hang / display driver timeout (TDR) on the host machine. Concurrently, the upstream server instance dedicates 100% of its processing cycles to compute this infinite physics loop, freezing the instance and dropping all active players. But this happens sometimes, not always.

(P.D: all the information (screenshots, screenrecords, logs...) and everything of that, I can't upload it because of the bad connection from user to mod via Discord, if you want more information, please, contact me to NicolasCosialls@outlook.com).

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