# Siemens SIMATIC CN 4100 denial-of-service flaw

Published: 2025-07-10 · Severity: routine · Sectors: manufacturing
Canonical: https://vorant.io/reports/623bb2e3-68b8-5859-8a6e-817e5b69cc17/siemens-simatic-cn-4100-denial-of-service-flaw

> Improper input validation in SIMATIC CN 4100 allows authenticated attackers to cause denial of service via SFTP file upload.

Siemens SIMATIC CN 4100 industrial control devices versions prior to V4.0 contain an improper input validation vulnerability (CWE-20) that allows an authenticated attacker with network access to upload arbitrary files to the device's SFTP folder, triggering a denial-of-service condition. The vulnerability requires low attack complexity and authenticated access; no public exploitation has been reported. CVSS v3.1 base score is 6.5, with CVSS v4.0 score of 7.1. The SIMATIC CN 4100 is an industrial controller deployed worldwide in critical manufacturing sectors. Siemens recommends immediate upgrade to V4.0 or later as the primary mitigation, supplemented by network segmentation and access control measures.

## Mentioned in this report

- Vulnerabilities: CVE-2025-40593

Source reporting: https://www.cisa.gov/news-events/ics-advisories/icsa-25-191-04

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