Improper input validation in Arm Mbed-Mqtt
CVE-2019-17210
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.
Vulnerability class: Drupalgeddon 2 (CVE-2018-7600)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.
EPSS exploit prediction
EPSS: 0.010 (62.0th percentile), scored .
Low probability of exploitation in the next 30 days, but still tracked. 62nd percentile — 62.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.010 · newest: 0.010 · change: 0.000
Affected products
- Arm Mbed-Mqtt — versions 2017-11-02
- Arm Mbed-Os
Weakness classification (CWE)
References
- github.com/ARMmbed/mbed-os/issues/11802 (Third Party Advisory, Issue Tracking)
Frequently asked questions
- What is CVE-2019-17210?
- CVE-2019-17210 is a high-severity vulnerability in Arm Mbed-Mqtt, classified under Improper Input Validation. CVSS score: 7.5/10. Published 2019-11-04.
- How severe is CVE-2019-17210?
- High severity. CVSS v3 base score is 7.5 out of 10.