CVE-2021-31884

Memory corruption via unterminated DHCP hostname option

Published Nov 9, 2021 · Updated Aug 3, 2024

Memory corruption in Siemens Nucleus RTOS DHCP clients allows adjacent attackers to read or write memory or interrupt service. The client assumes DHCP Hostname option data is null-terminated and reads or writes beyond its boundary when the global hostname is undefined. Exploitation requires a crafted DHCP response on the local network and an enabled DHCP client, which is disabled by default on APOGEE, TALON, and Desigo products.

CVSS severity8.8
High
EPSS probability1.50%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Memory corruption in Siemens Nucleus RTOS DHCP clients allows adjacent attackers to read or write memory or interrupt service. The client assumes DHCP Hostname option data is null-terminated and reads or writes beyond its boundary when the global hostname is undefined. Exploitation requires a crafted DHCP response on the local network and an enabled DHCP client, which is disabled by default on APOGEE, TALON, and Desigo products.

The record

CVE
CVE-2021-31884
Published
Nov 9, 2021
Updated
Aug 3, 2024
Vendor
Siemens
Product
Capital VSTAR
Classifications
CWE-170, T1557.003
Attack vector
adjacent
Privileges
unauthenticated

Timeline

How it unfolded

  1. Nov 9, 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?

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

  1. Affected versionversion=All versions with enabled Ethernet options

What conditions does exploitation require?

Attack vectoradjacent
Required privilegesunauthenticated

What is affected?

Siemens · Capital VSTARversion=All versions with enabled Ethernet options
Siemens · TALON TC Compact (BACnet)version=All versions < V3.5.4
Siemens · APOGEE PXC Modular (P2 Ethernet)version=All versions < V2.8.19
Siemens · Desigo PXC00-Uversion=All versions >= V2.3 and < V6.30.016
Siemens · Desigo PXC100-E.Dversion=All versions >= V2.3 and < V6.30.016
Siemens · APOGEE MBC (PPC) (BACnet)version=All versions
Siemens · Desigo PXC22-E.Dversion=All versions >= V2.3 and < V6.30.016
Siemens · APOGEE MEC (PPC) (BACnet)version=All versions
Siemens · Desigo PXM20-Eversion=All versions >= V2.3 and < V6.30.016
Siemens · Nucleus Source Codeversion=All versions
Siemens · Desigo PXC22.1-E.Dversion=All versions >= V2.3 and < V6.30.016
Siemens · Nucleus NET for Nucleus PLUSversion=All versions
Siemens · APOGEE MEC (PPC) (P2 Ethernet)version=All versions
Siemens · Nucleus ReadyStart V3version=All versions < V2017.02.4
Siemens · APOGEE PXC Compact (BACnet)version=All versions < V3.5.4
Siemens · TALON TC Modular (BACnet)version=All versions < V3.5.4
Siemens · Desigo PXC64-Uversion=All versions >= V2.3 and < V6.30.016
Siemens · APOGEE MBC (PPC) (P2 Ethernet)version=All versions
Siemens · Desigo PXC50-E.Dversion=All versions >= V2.3 and < V6.30.016
Siemens · Desigo PXC12-E.Dversion=All versions >= V2.3 and < V6.30.016
Siemens · Desigo PXC36.1-E.Dversion=All versions >= V2.3 and < V6.30.016
Siemens · APOGEE PXC Modular (BACnet)version=All versions < V3.5.4
Siemens · APOGEE PXC Compact (P2 Ethernet)version=All versions < V2.8.19
Siemens · Desigo PXC00-E.Dversion=All versions >= V2.3 and < V6.30.016
Siemens · Desigo PXC001-E.Dversion=All versions >= V2.3 and < V6.30.016
Siemens · Desigo PXC128-Uversion=All versions >= V2.3 and < V6.30.016
Siemens · Desigo PXC200-E.Dversion=All versions >= V2.3 and < V6.30.016

Published CVSS scores

8.8Siemens ProductCERTCVSS:3.1/AV:A/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 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-170Improper Null Termination
T1557.003Adversary-in-the-Middle: DHCP Spoofing

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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