CVE-2021-25671

Service interruption via crafted ARP packets

Published Jul 13, 2021 · Updated Aug 3, 2024

Denial of service in Siemens RWG1.M8, RWG1.M12, and RWG1.M12D before 1.16.16 allows attackers to interrupt operation via crafted ARP packets. The ARP protocol processing fails to limit resource allocation when handling specially crafted packets, leaving the controller unable to operate normally. Attackers must reach the same Layer 2 domain, and successful exploitation leaves the controller inoperative until it is restarted.

CVSS severity6.5
Medium
EPSS probability0.38%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in Siemens RWG1.M8, RWG1.M12, and RWG1.M12D before 1.16.16 allows attackers to interrupt operation via crafted ARP packets. The ARP protocol processing fails to limit resource allocation when handling specially crafted packets, leaving the controller unable to operate normally. Attackers must reach the same Layer 2 domain, and successful exploitation leaves the controller inoperative until it is restarted.

The record

CVE
CVE-2021-25671
Published
Jul 13, 2021
Updated
Aug 3, 2024
Vendor
Siemens
Product
RWG1.M12
Classifications
CWE-770, T1499
Attack vector
adjacent
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 13, 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 < V1.16.16

What conditions does exploitation require?

Attack vectoradjacent
Required privilegesunauthenticated

What is affected?

Siemens · RWG1.M12version=All versions < V1.16.16
Siemens · RWG1.M12Dversion=All versions < V1.16.16
Siemens · RWG1.M8version=All versions < V1.16.16

Published CVSS scores

4.3NIST NVDCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
3.3NIST NVDAV:A/AC:L/Au:N/C:N/I:N/A:P
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.

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-770Allocation of Resources Without Limits or Throttling
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

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Your stack

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