Insufficient publish message length validation in MQTT

published 2020-06-05 6y ago modified 2026-06-17 4mo ago also EUVD-2020-2536

cvss: 9.0; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 3.4%; EPSS 3.4% chance of exploitation in 30 days, percentile 88%
public exploits: 0; none known

The Zephyr MQTT parsing code performs insufficient checking of the length field on publish messages, allowing a buffer overflow and potentially remote code execution. NCC-ZEP-031 This issue affects: zephyrproject-rtos zephyr version 2.2.0 and later versions.

Patch / fix

links 1

github.com/zephyrproject-rtos/zephyr#23821 commit

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Exploit prediction

3.40% chance of exploitation in the next 30 days, higher than 88% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by	version	score	vector
CNA	3.1	9.0	CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H
NVD	3.1	9.8	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD	2.0	7.5	AV:N/AC:L/Au:N/C:P/I:P/A:P

Affected products

zephyrproject-rtos zephyr

Classification

Weakness

CWE-120 Buffer Copy without Checking Size of Input
CWE-129 Improper Validation of Array Index

References

github.com /zephyrproject-rtos/zephyr/pull/23821/commits/989c4713ba429aa5105fe476b4d629718f3e6082
patch, third-party-advisory
docs.zephyrproject.org /latest/security/vulnerabilities.html#cve-2020-10071
vendor-advisory
research.nccgroup.com /2020/05/26/research-report-zephyr-and-mcuboot-security-assessment
third-party-advisory
zephyrprojectsec.atlassian.net /browse/ZEPSEC-86
third-party-advisory

Sources

CVE List CVE-2020-10071
NVD CVE-2020-10071

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