CVE-2026-22925Network attack vector

Unauthenticated service interruption via unthrottled TCP SYN handling

Published May 12, 2026 · Updated May 12, 2026

Resource exhaustion in Siemens SIMATIC CN 4100 before 5.0 allows remote attackers to interrupt service with high-volume TCP SYN traffic. The TCP connection-handling path allocates system resources for incoming SYN packets without sufficient limits or throttling, allowing outstanding requests to exhaust capacity. No authentication or user interaction is required; sustained network traffic can make the communication node unavailable, with no reported confidentiality or integrity impact.

CVSS severity7.5
High
EPSS probability0.32%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Resource exhaustion in Siemens SIMATIC CN 4100 before 5.0 allows remote attackers to interrupt service with high-volume TCP SYN traffic. The TCP connection-handling path allocates system resources for incoming SYN packets without sufficient limits or throttling, allowing outstanding requests to exhaust capacity. No authentication or user interaction is required; sustained network traffic can make the communication node unavailable, with no reported confidentiality or integrity impact.

The record

CVE
CVE-2026-22925
Published
May 12, 2026
Updated
May 12, 2026
Vendor
Siemens
Product
SIMATIC CN 4100
Classifications
CWE-770, T1499.001
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 12, 2026CVE publishedPublication date reported by the CVE source.
  2. May 12, 2026Record 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 <V5.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Siemens · SIMATIC CN 4100version=0 <V5.0

Published CVSS scores

8.7Siemens ProductCERTCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
7.5Siemens ProductCERTCVSS:3.1/AV:N/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)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-770Allocation of Resources Without Limits or Throttling
T1499.001OS Exhaustion Flood

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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