CVE-2023-28116: Buffer overflow in L2CAP due to misconfigured MTU

Contiki-NG is an open-source, cross-platform operating system for internet of things (IoT) devices. In versions 4.8 and prior, an out-of-bounds write can occur in the BLE L2CAP module of the Contiki-NG operating system. The network stack of Contiki-NG uses a global buffer (packetbuf) for processing of packets, with the size of PACKETBUFSIZE. In particular, when using the BLE L2CAP module with the default configuration, the PACKETBUFSIZE value becomes larger then the actual size of the packetbuf. When large packets are processed by the L2CAP module, a buffer overflow can therefore occur when copying the packet data to the packetbuf. The vulnerability has been patched in the "develop" branch of Contiki-NG, and will be included in release 4.9. The problem can be worked around by applying the patch manually.