---
id: CVE-2021-42553
title: >-
  A buffer overflow vulnerability in stm32_mw_usb_host of STMicroelectronics in
  versions before 3.5.1 allows an attacker to execute arbitrary code when the
  descriptor contains more endpoints than USBH_MAX_NUM_ENDPOINTS
summary: >-
  A buffer overflow vulnerability in stm32_mw_usb_host of STMicroelectronics in
  versions before 3.5.1 allows an attacker to execute arbitrary code when the
  descriptor contains more endpoints than USBH_MAX_NUM_ENDPOINTS. The library is
  typi…
severity: medium
cvss: 6.8
cvssVector: 'CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H'
cwe:
  - CWE-120
  - CWE-120
vendor: st
product: stm32_mw_usb_host
affected:
  - stm32_mw_usb_host < 3.5.1
patched:
  - stm32_mw_usb_host 3.5.1
published: '2022-10-21'
updated: '2026-10-08'
sourceUpdated: '2026-10-08T18:23:29.090'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2021-42553'
references:
  - url: 'https://github.com/STMicroelectronics/stm32_mw_usb_host'
    label: vulnerability@ncsc.ch
  - url: 'https://github.com/STMicroelectronics/stm32_mw_usb_host/pull/4'
    label: vulnerability@ncsc.ch
  - url: 'https://github.com/STMicroelectronics/stm32_mw_usb_host'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://github.com/STMicroelectronics/stm32_mw_usb_host/pull/4'
    label: af854a3a-2127-422b-91ae-364da2661108
tags:
  - nvd
epss: 0.0106
epssPercentile: 0.63481
ingestedAt: '2026-10-08T18:58:11.290Z'
---

## Overview

A buffer overflow vulnerability in stm32_mw_usb_host of STMicroelectronics in versions before 3.5.1 allows an attacker to execute arbitrary code when the descriptor contains more endpoints than USBH_MAX_NUM_ENDPOINTS. The library is typically integrated when using a RTOS such as FreeRTOS on STM32 MCUs.

## Affected

- `stm32_mw_usb_host < 3.5.1`

## Remediation

Upgrade past the affected range:

- `stm32_mw_usb_host 3.5.1`