CVE Intelligence
Critical Access control

CVE-2023-29131 — A vulnerability has been identified in SIMATIC CN 4100 (All versions < V2.5). Affected device...

A vulnerability has been identified in SIMATIC CN 4100 (All versions < V2.5). Affected device consists of an incorrect default value in the SSH configuration. This could allow an attacker to bypass network isolation.

Published Jul 11, 2023 · Updated Oct 24, 2026 · Sources: CVE Program (cve.org) e CISA ADP, NIST National Vulnerability Database, GitHub Security Advisories · CNA: siemens

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 0.4% (30-day exploitation probability)+5
  • Technical severity (critical)+10

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
0.42%
ahead of 36% of scored CVEs · Oct 26, 2026
Affects
Siemens
SIMATIC CN 4100 and 1 more
CVSS base
10.0
Critical · 4 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
No
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.

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.

  1. Identify exposed assets running the affected vendor/product/version combinations (Siemens SIMATIC CN 4100, Siemens Simatic Cn 4100 Firmware).
  2. The attack is network-based and needs no privileges: restrict exposure (ACLs, VPN, WAF) until patched.
  3. Apply the fixed version or the patch documented under Remediation.
  4. Search available logs for exploit probes matching the vulnerability class (access control), errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

VendorProductVersionsStatusSource
Siemens SIMATIC CN 4100 version All versions < V2.5 Vulnerable CVE Program (cve.org) e CISA ADP
Siemens Simatic Cn 4100 Firmware < 2.5 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
Changed
Confidentiality
High
Integrity
High
Availability
High

Every base score collected

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

ScoreVersionSeverityExpl.ImpactScored by
10.0 CVSS 3.1 Critical 3.9 6.0 nvd@nist.gov via NIST National Vulnerability Database
7.4 CVSS 3.1 High 3.1 3.7 productcert@siemens.com via NIST National Vulnerability Database
7.4 CVSS 3.1 High — — GitHub, Inc. via GitHub Security Advisories
7.4 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:C/C:H/I:H/A:H (score shown at the top: nvd@nist.gov)
Scoring entities (NIST, CNA, ADP) score independently; each score is shown with its origin. For prioritization we use 10.0 (NVD (NIST)) as a conservative provisional reference — not a definitive official score.

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-276 · Incorrect Default Permissions

Other CVEs with this weakness →

EPSS over time FIRST

Oct 23, 2026 → Oct 26, 2026 · 4 reading(s) · max 0.42%

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).
  • Audit administrative actions and access to resources outside each user’s normal pattern.
web/proxy/WAF logsnetwork IDS/IPSauthentication logsapplication logs

Timeline

What happened to this CVE, newest first.

  • 2026
  • Fix documented
    Oct 24, 2026 · NIST National Vulnerability Database
  • Affected products added · siemens/simatic cn 4100 firmware
    Oct 24, 2026 · NIST National Vulnerability Database
  • CVSS changed · 7.4 → 10.0
    Oct 24, 2026 · NIST National Vulnerability Database
  • Source status changed · Published → Modified
    Oct 24, 2026 · NIST National Vulnerability Database
  • Record published
    Oct 24, 2026
  • Affected products added · siemens/simatic cn 4100
    Oct 24, 2026 · CVE Program (cve.org) e CISA ADP
  • CVSS changed · 7.4
    Oct 24, 2026 · CVE Program (cve.org) e CISA ADP
  • Source status changed · → Published
    Oct 24, 2026 · CVE Program (cve.org) e CISA ADP
  • SSVC assessment updated
    Oct 24, 2026 · CVE Program (cve.org) e CISA ADP
  • Record created in this database
    Oct 24, 2026 · Alertas do Telegram
  • 2023
  • CVE published
    Jul 11, 2023 · siemens

Source activity

Repeated readings are counted rather than listed.

  • 2× References added · Oct 24, 2026 – Oct 24, 2026
  • 1× Official description updated · Oct 24, 2026 – Oct 24, 2026

References

3 on the record

Elsewhere on this site

Siemens
every CVE for this vendor
Access control
same class
CWE-276
other pages naming this weakness

Related CVEs (same products)

  • CVE-2026-22925 A vulnerability has been identified in SIMATIC CN 4100 (All versions < V5.0). The affected... May 12, 2026
  • CVE-2026-22924 Siemens SIMATIC CN 4100 Missing Authentication (CWE-306) May 12, 2026
  • CVE-2026-31431 Linux Kernel Incorrect Resource Transfer Between Spheres Vulnerability KEV Apr 22, 2026
  • CVE-2026-2673 OpenSSL TLS 1.3 server may choose unexpected key agreement group Mar 13, 2026
  • CVE-2025-40937 A vulnerability has been identified in SIMATIC CN 4100 (All versions < V4.0.1). The affected... Dec 9, 2025
  • CVE-2025-40938 A vulnerability has been identified in SIMATIC CN 4100 (All versions < V4.0.1). The affected... 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-2023-29131 is "A vulnerability has been identified in SIMATIC CN 4100 (All versions < V2.5). Affected device...", rated Critical. 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 10.0 describes technical severity. EPSS 0.42% 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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