CVE-2021-31882

Denial of service via unchecked DHCP option length

Published Nov 9, 2021 · Updated Mar 11, 2025

Improper input validation in Siemens Capital Embedded AR Classic 431-422 and R20-11 before V2303 allows remote attackers to interrupt service. The Nucleus NET DHCP client processes DNS option 0x06 in an ACK without validating the option length. Exploitation requires access to the DHCP exchange and enabled DHCP client functionality; Siemens documents service interruption but not whether the ECU hangs, crashes, or reboots.

CVSS severity6.5
Medium
EPSS probability1.52%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper input validation in Siemens Capital Embedded AR Classic 431-422 and R20-11 before V2303 allows remote attackers to interrupt service. The Nucleus NET DHCP client processes DNS option 0x06 in an ACK without validating the option length. Exploitation requires access to the DHCP exchange and enabled DHCP client functionality; Siemens documents service interruption but not whether the ECU hangs, crashes, or reboots.

The record

CVE
CVE-2021-31882
Published
Nov 9, 2021
Updated
Mar 11, 2025
Vendor
Siemens
Product
Capital Embedded AR Classic
Classifications
CWE-119, T1499.004
Attack vector
adjacent
Privileges
unauthenticated

Timeline

How it unfolded

  1. Nov 9, 2021CVE publishedPublication date reported by the CVE source.
  2. Mar 11, 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?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <*
  2. Affected versionversion=0 <V2303

What conditions does exploitation require?

Attack vectoradjacent
Required privilegesunauthenticated

What is affected?

Siemens · Capital Embedded AR Classicversion=0 <*; version=0 <V2303

Published CVSS scores

6.5Siemens ProductCERTCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/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.

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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)
Vectoradjacent
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-119Improper Restriction of Operations within the Bounds of a Memory Buffer
T1499.004Application or System Exploitation

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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