CVE-2019-17212

Published Nov 5, 2019 CVSS 3.1 · 9.8 Critical EPSS 3.1% KEV · Not listed

Description

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.

Affected Products

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions

n/a

affected

Version	Status	Constraints
`n/a`	affected	—

Configuration 1 [-]

OR	cpe:2.3:o:mbed:mbed:5.13.2:::::::*
	cpe:2.3:o:mbed:mbed:5.14.0:::::::*

No data.

No data available yet.

Remediation

No solution or workaround provided in the CVE record

Tracking

Advisories

Source	ID	Title
EUVD	EUVD-2019-7632	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.

Metrics

No CVSS v4.0

Attack Vector Network

Attack Complexity Low

Privileges Required None

Scope Unchanged

Confidentiality Impact High

Integrity Impact High

Availability Impact High

User Interaction None

No CVSS v3.0

Access Vector Network

Access Complexity Low

Authentication None

Confidentiality Impact Complete

Integrity Impact Complete

Availability Impact Complete

This CVE is not in the KEV list.

Exploit prediction score: 3.1% (3.060% probability within 30 days)

Key SSVC decision points have not yet been added.

References

Link	Providers
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