A buffer over-read was discovered in the CoAP library in Arm Mbed OS 5.15.3. The CoAP parser is responsible for parsing received CoAP packets. The function sn_coap_parser_options_parse() parses the CoAP packet header starting from the message token. The length of the token in the received message is provided in the first byte parsed by the sn_coap_parser_options_parse() function. The length encoded in the message is not validated against the actual input buffer length before accessing the token. As a result, memory access outside of the intended boundary of the buffer may occur.
CWE-125 - Out-of-Bounds Read
Out-of-bounds read is a vulnerability that allows access to memory beyond the authorized accessible location. Such a vulnerability compromises the confidentiality of the trusted environment in the application and enables an attacker to launch further attacks by leveraging the exposed information.