CVE-2021-31344Network attack vector

Arbitrary host spoofing via fake IP options

Published Nov 9, 2021 · Updated Mar 11, 2025

Type confusion in Siemens Capital Embedded AR Classic 431-422 and R20-11 allows remote attackers to send ICMP echo replies to arbitrary hosts via fake IP options. The network stack accepts ICMP echo packets containing forged IP options and emits replies using attacker-selected destinations, creating an integrity-impacting spoofing primitive. No authentication or user interaction is required, but the attacker must reach the device over the network; the advisory does not report confidentiality loss or service interruption.

CVSS severity5.3
Medium
EPSS probability1.46%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Type confusion in Siemens Capital Embedded AR Classic 431-422 and R20-11 allows remote attackers to send ICMP echo replies to arbitrary hosts via fake IP options. The network stack accepts ICMP echo packets containing forged IP options and emits replies using attacker-selected destinations, creating an integrity-impacting spoofing primitive. No authentication or user interaction is required, but the attacker must reach the device over the network; the advisory does not report confidentiality loss or service interruption.

The record

CVE
CVE-2021-31344
Published
Nov 9, 2021
Updated
Mar 11, 2025
Vendor
Siemens
Product
Capital Embedded AR Classic
Classifications
CWE-843
Attack vector
network
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 vectornetwork
Required privilegesunauthenticated

What is affected?

Siemens · Capital Embedded AR Classicversion=0 <*; version=0 <V2303
Siemens · PLUSCONTROL 1st Genversion=All versions
Siemens · SIMOTICS CONNECT 400version=All versions < V0.5.0.0; version=All versions < V1.0.0.0

Published CVSS scores

6.9Siemens AGCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N
5.3Siemens AGCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

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)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-843Access of Resource Using Incompatible Type ('Type Confusion')

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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