CVE-2021-31346Network attack vector

Memory disclosure or service interruption via ICMP length

Published Nov 9, 2021 · Updated Mar 11, 2025

Improper ICMP length validation in affected Siemens products allows remote attackers to disclose memory or interrupt service. The Nucleus NET stack trusts the total ICMP payload length declared in the IP header without checking it against the network buffer's memory organization. No authentication or user interaction is required; crafted network packets expose memory contents or interrupt device service, depending on the implementation.

CVSS severity8.2
High
EPSS probability1.97%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Improper ICMP length validation in affected Siemens products allows remote attackers to disclose memory or interrupt service. The Nucleus NET stack trusts the total ICMP payload length declared in the IP header without checking it against the network buffer's memory organization. No authentication or user interaction is required; crafted network packets expose memory contents or interrupt device service, depending on the implementation.

The record

CVE
CVE-2021-31346
Published
Nov 9, 2021
Updated
Mar 11, 2025
Vendor
Siemens
Product
Capital Embedded AR Classic
Classifications
CWE-1284, T1499
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

Compare your product and version with the public record. A matching version still requires validation against your environment.

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

6.4NIST NVDAV:N/AC:L/Au:N/C:P/I:N/A:P
8.2Siemens ProductCERTCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H
9.1NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/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.

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-1284Improper Validation of Specified Quantity in Input
T1499Endpoint Denial of Service

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

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo