In rawTCP.cpp in Matter (aka connectedhomeip or Project CHIP) through 1.4.0.0 before 27ca6ec, there is a NULL pointer dereference in TCPBase::ProcessSingleMessage via TCP packets with zero messageSize, leading to denial of service.
A NULL pointer dereference occurs when the application dereferences a pointer that it expects to be valid, but is NULL, typically causing a crash or exit.