CVE-2020-14936: Out-of-bounds Write

Buffer overflows were discovered in Contiki-NG 4.4 through 4.5, in the SNMP agent. Functions parsing the OIDs in SNMP requests lack sufficient allocated target-buffer capacity verification when writing parsed OID values. The function snmp_oid_decode_oid() may overwrite memory areas beyond the provided target buffer, when called from snmp_message_decode() upon an SNMP request reception. Because the content of the write operations is externally provided in the SNMP requests, it enables a remote overwrite of an IoT device's memory regions beyond the allocated buffer. This overflow may allow remote overwrite of stack and statically allocated variables memory regions by sending a crafted SNMP request.