# CVE-2025-40940: A vulnerability has been identified in SIMATIC CN 4100 (All versions < V4.0.1). The affected application exhibits…

Source: https://junglewise.ai/threats/cve-2025-40940-a-vulnerability-has-been-identified-in-simatic-cn-4100-all  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2025-12-09  
License: CC BY 4.0 with a link back

CVE-2025-40940 · Severity: medium · CVSS 4.9 · Published 2025-12-09

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.

Technologies: [Siemens SIMATIC CN 4100](https://junglewise.ai/threats/technologies/simatic-cn-4100), [Siemens Simatic Cn 4100 Firmware](https://junglewise.ai/threats/technologies/simatic-cn-4100-firmware). Vendors: [Siemens](https://junglewise.ai/threats/vendors/siemens).

## Quick answers

**Is CVE-2025-40940 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2025-40940 being exploited in the wild.

**How severe is CVE-2025-40940?** Medium severity, with a CVSS score of 4.9, published 9 December 2025.

**Which products and versions are affected?** Siemens SIMATIC CN 4100, Siemens Simatic Cn 4100 Firmware. The advisory does not name versions.

**Is there a fix for CVE-2025-40940?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**Am I affected by CVE-2025-40940?** Check whether you run Siemens SIMATIC CN 4100 or Siemens Simatic Cn 4100 Firmware. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Affected products

- Siemens SIMATIC CN 4100
- Siemens Simatic Cn 4100 Firmware

## Related threats

- [Siemens SIMATIC CN 4100 resource exhaustion via TCP SYN flood](https://junglewise.ai/threats/cve-2026-22925-siemens-simatic-cn-4100-resource-exhaustion-via-tcp-syn-flood)
- [Siemens SIMATIC CN 4100 missing authentication and resource exhaustion](https://junglewise.ai/threats/cve-2026-22924-siemens-simatic-cn-4100-missing-authentication-and-resource)
- [Linux Kernel crypto algif_aead improper memory handling](https://junglewise.ai/threats/cve-2026-31431-linux-kernel-crypto-algif-aead-improper-memory-handling)
- [OpenSSL uninitialized memory disclosure in RSASVE key encapsulation](https://junglewise.ai/threats/cve-2026-31790-openssl-uninitialized-memory-disclosure-in-rsasve-key)
- [OpenSSL heap buffer overflow in buf2hex conversion](https://junglewise.ai/threats/cve-2026-31789-openssl-heap-buffer-overflow-in-buf2hex-conversion)