CVE-2019-17211: Mbed

Critical severity, CVSS 9.8. EPSS: 2.6% chance of exploitation in the next 30 days.

An integer overflow was discovered in the CoAP library in Arm Mbed OS 5.14.0. The function sn_coap_builder_calc_needed_packet_data_size_2() is used to calculate the required memory for the CoAP message from the sn_coap_hdr_s data structure. Both returned_byte_count and src_coap_msg_ptr->payload_len are of type uint16_t. When added together, the result returned_byte_count can wrap around the maximum uint16_t value. As a result, insufficient buffer space is allocated for the corresponding CoAP message.

Affected products

• Mbed Mbed: version 5.13.2 only; version 5.14.0 only

Published 2019-11-05. Last modified 2026-06-17.