Buffer Over-read Vulnerability in Arm Mbed OS CoAP Library

CVE-2020-12884

Summary

A buffer over-read issue exists in the CoAP library of Arm Mbed OS 5.15.3. This vulnerability arises when the CoAP parser processes packets that may contain multiple options. Specifically, the function sn_coap_parser_options_parse_multiple_options() fails to conduct an out-of-bounds check on packet_data_pptr after incrementing it by option_len. While there is a validation check for temp_parsed_uri_query_ptr, it relies on allocated heap memory rather than the actual size of input data. Thus, access can potentially go beyond the intended packet buffer boundary, posing significant security risks.

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