CVE-2021-34267Public exploit

System hang via unchecked USB endpoint directions

Published Jul 22, 2021 · Updated Aug 4, 2024

Denial of service in STMicroelectronics STM32Cube Middleware 1.8.0 and earlier allows physically proximate attackers to hang the system. USBH_MSC_InterfaceInit() trusts endpoint direction bits and initializes only the IN or OUT pipe when both descriptors report the same direction. A crafted USB mass-storage device must be physically connected; communication with its malformed endpoint layout leaves one pipe uninitialized and hangs the host.

CVSS severity4.6
Medium
EPSS probability0.35%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in STMicroelectronics STM32Cube Middleware 1.8.0 and earlier allows physically proximate attackers to hang the system. USBH_MSC_InterfaceInit() trusts endpoint direction bits and initializes only the IN or OUT pipe when both descriptors report the same direction. A crafted USB mass-storage device must be physically connected; communication with its malformed endpoint layout leaves one pipe uninitialized and hangs the host.

The record

CVE
CVE-2021-34267
Published
Jul 22, 2021
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
T1200
Attack vector
physical
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 22, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectorphysical
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

4.6NIST NVDCVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
2.1NIST NVDAV:L/AC:L/Au:N/C:N/I:N/A:P

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorphysical
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

T1200Hardware Additions

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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