CVE-2021-38111Public exploit

Over-the-air code execution via unchecked packet length

Published Aug 4, 2021 · Updated May 5, 2025

Buffer overflow in DEF CON 27 badge firmware allows physically proximate attackers to execute code via an oversized NFMI packet. KL_GetPacket fails to bound received packet data to its stack buffer, allowing excess data to overwrite saved control state. Exploitation requires NFMI radio proximity but no authentication or user interaction; a successful overwrite permits arbitrary firmware code execution.

CVSS severity8.8
High
EPSS probability1.33%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Buffer overflow in DEF CON 27 badge firmware allows physically proximate attackers to execute code via an oversized NFMI packet. KL_GetPacket fails to bound received packet data to its stack buffer, allowing excess data to overwrite saved control state. Exploitation requires NFMI radio proximity but no authentication or user interaction; a successful overwrite permits arbitrary firmware code execution.

The record

CVE
CVE-2021-38111
Published
Aug 4, 2021
Updated
May 5, 2025
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-120, T1210
Attack vector
adjacent
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 4, 2021CVE publishedPublication date reported by the CVE source.
  2. May 5, 2025Record 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 vectoradjacent
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

8.8CISA-ADPCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
8.8NIST NVDCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
5.8NIST NVDAV:A/AC:L/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.

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)
Vectoradjacent
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-120Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')
T1210Exploitation of Remote Services

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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