High Denial of service

CVE-2026-22925 — Allocation of Resources Without Limits or Throttling in Siemens SIMATIC CN 4100

A vulnerability has been identified in SIMATIC CN 4100 (All versions < V5.0). The affected application is susceptible to resource exhaustion when subjected to high volume of TCP SYN packets This could allow an attacker to render the service unavailable and cause denial-of-service conditions by overwhelming system resources.

Published May 12, 2026 · Updated Oct 13, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP · CNA: siemens

Low

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.

How the score was calculated

EPSS 0.3% (30-day exploitation probability)+4
Technical severity (high)+6
Automatable exploitation (SSVC)+3

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation

Not confirmed

Not in CISA KEV — an absence of record, not proof it is unexploited.

EPSS FIRST

0.32%

ahead of 24% of scored CVEs · Oct 14, 2026

Affects

Siemens

SIMATIC CN 4100 and 1 more

CVSS base

7.5

High · 2 source(s)

CISA SSVC assessment CISA

Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.

Exploitation

None

none · proof-of-concept · active

Automatable

Yes

can an attacker script the kill-chain steps

Technical impact

Partial

partial · total control of the vulnerable component

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

Documented mitigation — cert-portal.siemens.com (NIST National Vulnerability Database)

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

Identify exposed assets running the affected vendor/product/version combinations (Siemens SIMATIC CN 4100, Siemens Simatic Cn 4100 Firmware).
The attack is network-based and needs no privileges: restrict exposure (ACLs, VPN, WAF) until patched.
Apply the documented mitigations until a definitive fix is available.
Search available logs for exploit probes matching the vulnerability class (denial of service), errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

Vendor	Product	Versions	Status	Source
Siemens	SIMATIC CN 4100	< V5.0	Vulnerable	CVE Program (cve.org) e CISA ADP
Siemens	Simatic Cn 4100 Firmware	< 5.0	Vulnerable	NIST National Vulnerability Database

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Attack vector

Network

Attack complexity

Low

Privileges required

None

User interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

None

Availability

High

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

Score	Version	Severity	Expl.	Impact	Scored by
8.7	CVSS 4.0	High	—	—	productcert@siemens.com via NIST National Vulnerability Database
8.7	CVSS 4.0	High	—	—	siemens via CVE Program (cve.org) e CISA ADP
7.5	CVSS 3.1	High	3.9	3.6	productcert@siemens.com via NIST National Vulnerability Database
7.5	CVSS 3.1	High	—	—	siemens via CVE Program (cve.org) e CISA ADP

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H (score shown at the top: productcert@siemens.com)

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-770 · Allocation of Resources Without Limits or Throttling

Other CVEs with this weakness →

EPSS over time FIRST

Oct 13, 2026 → Oct 14, 2026 · 2 reading(s) · max 0.32%

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).
Track CPU/memory spikes and availability drops correlated with request patterns.

web/proxy/WAF logsnetwork IDS/IPSresource metrics

Timeline

What happened to this CVE, newest first.

2026
Affected products added · siemens/simatic cn 4100
Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
SSVC assessment updated
Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
Record published
Oct 13, 2026
Fix documented
Oct 13, 2026 · NIST National Vulnerability Database
CVSS changed · 7.5
Oct 13, 2026 · NIST National Vulnerability Database
Source status changed · → Analyzed
Oct 13, 2026 · NIST National Vulnerability Database
Record created in this database
Oct 13, 2026 · NIST National Vulnerability Database
CVE published
May 12, 2026 · siemens

Source activity

Repeated readings are counted rather than listed.

1× Official description updated · Oct 13, 2026 – Oct 13, 2026

References

1 on the record

cert-portal.siemens.com/productcert/html/ssa-032379.html
Mitigation, Vendor Advisory, NIST National Vulnerability Database

Elsewhere on this site

Siemens
every CVE for this vendor

Denial of service
same class

CWE-770
other pages naming this weakness

Related CVEs (same products)

Critical CVE-2026-22924 Missing Authentication for Critical Function in Siemens Simatic Cn 4100 Firmware May 12, 2026
High CVE-2026-31431 Linux Kernel Incorrect Resource Transfer Between Spheres Vulnerability KEV Apr 22, 2026
Medium CVE-2026-2673 OpenSSL TLS 1.3 server may choose unexpected key agreement group Mar 13, 2026
High CVE-2025-40937 Command Injection in Siemens Simatic Cn 4100 Firmware Dec 9, 2025
Critical CVE-2025-40938 Use of Hard-coded Credentials in Siemens Simatic Cn 4100 Firmware Dec 9, 2025
Medium CVE-2025-40939 Improper Access Control in Siemens Simatic Cn 4100 Firmware Dec 9, 2025

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2026-22925 is "Allocation of Resources Without Limits or Throttling in Siemens SIMATIC CN 4100", rated High. It affects SIMATIC CN 4100 (Siemens); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 7.5 describes technical severity. EPSS 0.32% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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