CVE-2020-27212Public exploit

Debug access via boot-time RDP fault injection

Published May 21, 2021 · Updated Aug 4, 2024

Incorrect access control in STMicroelectronics STM32L4 devices through 2020-10-19 allows physically proximate attackers to enable debug access. A precisely timed power glitch during boot disrupts transfer of the RDP option byte into an internal register, causing level 2 to be interpreted as level 1. Physical possession, access to the device's power and debug interfaces, and glitching equipment are required; the downgrade exposes the limited debug access available at RDP level 1.

CVSS severity7.0
High
EPSS probability0.34%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Incorrect access control in STMicroelectronics STM32L4 devices through 2020-10-19 allows physically proximate attackers to enable debug access. A precisely timed power glitch during boot disrupts transfer of the RDP option byte into an internal register, causing level 2 to be interpreted as level 1. Physical possession, access to the device's power and debug interfaces, and glitching equipment are required; the downgrade exposes the limited debug access available at RDP level 1.

The record

CVE
CVE-2020-27212
Published
May 21, 2021
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-74
Attack vector
physical
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 21, 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

7.0NIST NVDCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
4.4NIST NVDAV:L/AC:M/Au:N/C:P/I:P/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

CWE-74Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection')

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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