CVE-2025-40938: Siemens SIMATIC CN 4100 · Use of Hard-coded Credentials
Affects Siemens SIMATIC CN 4100Source CVE Database V5
Not known to be exploited · CVSS 8.1 High.
Data as of 26 Oct 2026, 17:16 UTC
- EPSS
- 0.3% chance of exploitation in 30 days – higher than 31% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:HExploitation evidence
Disclosed: evidence found.
CVE published 9 Dec 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.
What to do
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| Siemens SIMATIC CN 4100 | Affected
| Fixed in– |
AI-suggested
Immediate mitigation should focus on network-level controls such as isolating SIMATIC CN 4100 devices within dedicated industrial control system (ICS) networks and restricting access to trusted administrators only. Implement strict firewall rules to limit inbound traffic to these devices and monitor network traffic for unusual access patterns. Employ intrusion detection systems (IDS) tailored for ICS environments to detect exploitation attempts. Where possible, replace affected devices with versions V4.0.1 or later once available. Conduct thorough audits of device configurations to identify and remove any default or hard-coded credentials. Additionally, implement multi-factor authentication on management interfaces if supported, and maintain robust logging and alerting to detect unauthorized access attempts promptly.
Description
A vulnerability has been identified in SIMATIC CN 4100 (All versions < V4.0.1). The affected device stores sensitive information in the firmware. This could allow an attacker to access and misuse this information, potentially impacting the device’s confidentiality, integrity, and availability.