Is CVE-2021-42553 actively exploited?

No active exploitation of CVE-2021-42553 has been confirmed so far. Continue monitoring, as exploit status can change.

Can CVE-2021-42553 be exploited remotely?

Yes. CVE-2021-42553 is exploitable remotely over the network (CVSS attack vector: Network).

What is the CVSS score of CVE-2021-42553?

CVE-2021-42553 has a CVSS score of 9.8 (CRITICAL).

HOME VULNERABILITIESCVE-2021-42553

CRITICAL

CVE-2021-42553

CWE-120Published: October 21, 2022· Updated: Jun 17, 2026

9.8

CVSS v3.1

Official Description

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.

NVD Source

Technical Analysis

CVE-2021-42553 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.

A successful exploit results in complete confidentiality breach (data exposure), full integrity compromise (data manipulation), availability disruption (denial of service), with a CVSS base score of 9.8.