CVE-2021-40154

Protected flash disclosure via oversized USB descriptor request

Published Dec 1, 2021 · Updated Aug 4, 2024

Buffer over-read in NXP LPC55S69 before A3 allows physically proximate attackers to read protected flash memory through USB ISP. The USB enumeration packet handler trusts a crafted wLength in a GET Descriptor Configuration request and returns memory beyond the intended descriptor buffer. The device must be in ISP or SDP mode, or run affected USB example code, and the resulting disclosure is limited to memory contents.

CVSS severity5.5
Medium
EPSS probability0.73%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Buffer over-read in NXP LPC55S69 before A3 allows physically proximate attackers to read protected flash memory through USB ISP. The USB enumeration packet handler trusts a crafted wLength in a GET Descriptor Configuration request and returns memory beyond the intended descriptor buffer. The device must be in ISP or SDP mode, or run affected USB example code, and the resulting disclosure is limited to memory contents.

The record

CVE
CVE-2021-40154
Published
Dec 1, 2021
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-125, T1005
Attack vector
physical
Privileges
Unavailable

Timeline

How it unfolded

  1. Dec 1, 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 privilegesUnavailable in this record.

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

2.1NIST NVDAV:L/AC:L/Au:N/C:P/I:N/A:N
5.5NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
6.1MITRECVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:L

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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

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
PrivilegesUnavailable
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-125Out-of-bounds Read
T1005Data from Local System

Public exploit references

No public exploit references are available in this record.

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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