Vulnerability Details CVE-2019-17212
Buffer overflows were discovered in the CoAP library in Arm Mbed OS 5.14.0. The CoAP parser is responsible for parsing received CoAP packets. The function sn_coap_parser_options_parse() parses CoAP input linearly using a while loop. Once an option is parsed in a loop, the current point (*packet_data_pptr) is increased correspondingly. The pointer is restricted by the size of the received buffer, as well as by the 0xFF delimiter byte. Inside each while loop, the check of the value of *packet_data_pptr is not strictly enforced. More specifically, inside a loop, *packet_data_pptr could be increased and then dereferenced without checking. Moreover, there are many other functions in the format of sn_coap_parser_****() that do not check whether the pointer is within the bounds of the allocated buffer. All of these lead to heap-based or stack-based buffer overflows, depending on how the CoAP packet buffer is allocated.
Exploit prediction scoring system (EPSS) score
EPSS Score 0.018
EPSS Ranking 82.0%
CVSS Severity
CVSS v3 Score 9.8
CVSS v2 Score 10.0
References
- https://github.com/ARMmbed/mbed-os/blob/d91ed5fa42ea0f32e4422a3c562e7b045a17da40/features/frameworks/mbed-coap/source/sn_coap_parser.c#L257
- https://github.com/ARMmbed/mbed-os/blob/d91ed5fa42ea0f32e4422a3c562e7b045a17da40/features/frameworks/mbed-coap/source/sn_coap_parser.c#L301
- https://github.com/ARMmbed/mbed-os/blob/d91ed5fa42ea0f32e4422a3c562e7b045a17da40/features/frameworks/mbed-coap/source/sn_coap_parser.c#L310
- https://github.com/ARMmbed/mbed-os/blob/d91ed5fa42ea0f32e4422a3c562e7b045a17da40/features/frameworks/mbed-coap/source/sn_coap_parser.c#L313
- https://github.com/ARMmbed/mbed-os/blob/d91ed5fa42ea0f32e4422a3c562e7b045a17da40/features/frameworks/mbed-coap/source/sn_coap_parser.c#L331
- https://github.com/ARMmbed/mbed-os/blob/d91ed5fa42ea0f32e4422a3c562e7b045a17da40/features/frameworks/mbed-coap/source/sn_coap_parser.c#L660
- https://github.com/ARMmbed/mbed-os/issues/11803
- https://github.com/ARMmbed/mbed-os/blob/d91ed5fa42ea0f32e4422a3c562e7b045a17da40/features/frameworks/mbed-coap/source/sn_coap_parser.c#L257
- https://github.com/ARMmbed/mbed-os/blob/d91ed5fa42ea0f32e4422a3c562e7b045a17da40/features/frameworks/mbed-coap/source/sn_coap_parser.c#L301
- https://github.com/ARMmbed/mbed-os/blob/d91ed5fa42ea0f32e4422a3c562e7b045a17da40/features/frameworks/mbed-coap/source/sn_coap_parser.c#L310
- https://github.com/ARMmbed/mbed-os/blob/d91ed5fa42ea0f32e4422a3c562e7b045a17da40/features/frameworks/mbed-coap/source/sn_coap_parser.c#L313
- https://github.com/ARMmbed/mbed-os/blob/d91ed5fa42ea0f32e4422a3c562e7b045a17da40/features/frameworks/mbed-coap/source/sn_coap_parser.c#L331
- https://github.com/ARMmbed/mbed-os/blob/d91ed5fa42ea0f32e4422a3c562e7b045a17da40/features/frameworks/mbed-coap/source/sn_coap_parser.c#L660
- https://github.com/ARMmbed/mbed-os/issues/11803