CVE-2020-12884: arm mbed_os Out-of-bounds Read

Vulnerability summary

CVE-2020-12884 is a critical (CVSS 9.1) Out-of-bounds Read vulnerability in arm mbed_os. EPSS estimates a 1.35% chance of exploitation in the next 30 days, higher than 71.1% of scored vulnerabilities.

Timeline

1. 18-06-2020
   PublishedVulnerability first disclosed.
2. 04-08-2024
   Last modifiedVulnerability information updated.

Description

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_multiple_options() parses CoAP options that may occur multiple consecutive times in a single packet. While processing the options, packet_data_pptr is accessed after being incremented by option_len without a prior out-of-bounds memory check. The temp_parsed_uri_query_ptr is validated for a correct range, but the range valid for temp_parsed_uri_query_ptr is derived from the amount of allocated heap memory, not the actual input size. Therefore the check of temp_parsed_uri_query_ptr may be insufficient for safe access to the area pointed to by packet_data_pptr. As a result, access to a memory area outside of the intended boundary of the packet buffer is made.

• CWE-125Out-of-bounds ReadThe product reads data past the end, or before the beginning, of the intended buffer.