CVE-2021-31881

Service interruption via unchecked DHCP Vendor option length

Published Nov 9, 2021 · Updated Mar 11, 2025

Out-of-bounds read in Siemens Capital Embedded AR Classic allows adjacent attackers to interrupt service via a crafted DHCP OFFER. The Nucleus NET DHCP client processes Vendor options without validating their declared length before reading them. Reachability requires enabled DHCP client functionality and local-network access; all 431-422 versions and R20-11 before V2303 are affected.

CVSS severity7.1
High
EPSS probability1.53%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Out-of-bounds read in Siemens Capital Embedded AR Classic allows adjacent attackers to interrupt service via a crafted DHCP OFFER. The Nucleus NET DHCP client processes Vendor options without validating their declared length before reading them. Reachability requires enabled DHCP client functionality and local-network access; all 431-422 versions and R20-11 before V2303 are affected.

The record

CVE
CVE-2021-31881
Published
Nov 9, 2021
Updated
Mar 11, 2025
Vendor
Siemens
Product
Capital Embedded AR Classic
Classifications
CWE-125, 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

7.1Siemens AGCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H
7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
5.0NIST NVDAV:N/AC:L/Au:N/C:N/I:N/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 exploitUnconfirmed

Weakness, pattern, technique

CWE-125Out-of-bounds Read
T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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