title: Buffer overflow in L2CAP due to misconfigured MTU
description: 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 PACKETBUF_SIZE. In particular, when using the BLE L2CAP module with the default configuration, the PACKETBUF_SIZE 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.
problem types: CWE-120: Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')
affected:
{
vendor: contiki-ng
product: contiki-ng
versions:
version: <= 4.8, status: affected
}
metrics:
cvssV3_1: [
attackComplexity: HIGH
attackVector: NETWORK
availabilityImpact: HIGH
baseScore: 8.1
baseSeverity: HIGH
confidentialityImpact: HIGH
integrityImpact: HIGH
privilegesRequired: NONE
scope: UNCHANGED
userInteraction: NONE
vectorString: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
version: 3.1
]