CVE-2021-23906

Code execution via unchecked HiQnet message length

Published May 13, 2021 · Updated Aug 3, 2024

Buffer overflow in Mercedes-Benz MBUX Headunit NTG6 through 2021 allows physically proximate attackers to execute code via HiQnet. ComPort::processTcpMessage trusts the header's Message Length when calculating the next message address, so an oversized value causes an invalid memory read. Reaching TCP port 3804 requires access to the head unit intranet; successful exploitation grants code execution in AudioManager.

CVSS severity6.8
Medium
EPSS probability0.80%
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 Mercedes-Benz MBUX Headunit NTG6 through 2021 allows physically proximate attackers to execute code via HiQnet. ComPort::processTcpMessage trusts the header's Message Length when calculating the next message address, so an oversized value causes an invalid memory read. Reaching TCP port 3804 requires access to the head unit intranet; successful exploitation grants code execution in AudioManager.

The record

CVE
CVE-2021-23906
Published
May 13, 2021
Updated
Aug 3, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-20, T1210
Attack vector
physical
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 13, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 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

2.1NIST NVDAV:L/AC:L/Au:N/C:P/I:N/A:N
1.8MITRECVSS:3.1/AV:P/AC:H/PR:N/UI:R/S:U/C:N/I:L/A:N
6.8NIST NVDCVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorphysical
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-20Improper Input Validation
T1210Exploitation of Remote Services

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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