CVE-2019-17210 Information

Description

A denial-of-service issue was discovered in the MQTT library in Arm Mbed OS 2017-11-02. The function readMQTTLenString() is called by the function MQTTDeserialize_publish() to get the length and content of the MQTT topic name. In the function readMQTTLenString() mqttstring-lenstring.len is a part of user input which can be manipulated. An attacker can simply change it to a larger value to invalidate the if statement so that the statements inside the if statement are skipped letting the value of mqttstring-lenstring.data default to zero. Later curn is accessed which points to mqttstring-lenstring.data. On an Arm Cortex-M chip the value at address 0x0 is actually the initialization value for the MSP register. It is highly dependent on the actual firmware. Therefore the behavior of the program is unpredictable from this time on.

CVSS Vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Reference

https://github.com/ARMmbed/mbed-os/issues/11802

Attack Complexity

LOW

Privileges Required

NONE

User Interaction Required

NONE

Scope

NONE

Confidentiality Impact

UNCHANGED

Integrity Impact

NONE

Availability Impact

NONE

Base Score

HIGH

Base Severity

7.5