SIMATIC PCS neo V4.1: Stack-based Buffer Overflow
CVE-2025-40795 is a critical-severity stack-based buffer overflow vulnerability in SIMATIC PCS neo V4.1 from Siemens, with a CVSS 3.1 base score of 9.8 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. Affected SIMATIC PCS neo V4.1 versions: all versions. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.71% chance of exploitation within 30 days, higher than 54% of scored CVEs.
Critical severity: a successful attack would have severe impact.
What to do
- Update SIMATIC PCS neo V6.0 to V6.0 SP1 Update 1 or a later version.
- Update User Management Component (UMC) to V2.15.1.3 or a later version.
- Update User Management Component to 2.15.1.3 or a later version.
- Read the advisory on cert-portal.siemens.com for workarounds and exact fixed builds.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Siemens | SIMATIC PCS neo V4.1 | all versions | Not stated |
| Siemens | SIMATIC PCS neo V5.0 | all versions | Not stated |
| Siemens | SIMATIC PCS neo V6.0 | before V6.0 SP1 Update 1 | V6.0 SP1 Update 1 |
| Siemens | User Management Component (UMC) | before V2.15.1.3 | V2.15.1.3 |
| Siemens | Simatic Pcs Neo | 4.1; 5.0 | Not stated |
| Siemens | User Management Component | before 2.15.1.3 | 2.15.1.3 |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H. Scored by CNA (siemens.com).
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 4.0 | 9.3 | Critical | CNA (siemens.com) |
| CVSS 3.1 | 9.8 | Critical | CNA (siemens.com) |
Official description
A vulnerability has been identified in SIMATIC PCS neo V4.1 (All versions), SIMATIC PCS neo V5.0 (All versions), SIMATIC PCS neo V6.0 (All versions < V6.0 SP1 Update 1), User Management Component (UMC) (All versions < V2.15.1.3). Affected products contain a stack-based buffer overflow vulnerability in the integrated UMC component. This could allow an unauthenticated remote attacker to execute arbitrary code or to cause a denial of service condition.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Stack-based Buffer Overflow
The product writes past the end of a buffer that was allocated on the stack.
How developers prevent this class of flaw
- Use automatic buffer overflow detection mechanisms that are offered by certain compilers or compiler extensions. Examples include: the Microsoft Visual Studio /GS flag, Fedora/Red Hat FORTIFY_SOURCE GCC flag, StackGuard, and ProPolice, which provide various mechanisms including canary-based detection and range/index checking. D3-SFCV (Stack Frame Canary Validation) from D3FEND discusses canary-based detection in detail.
- Use an abstraction library to abstract away risky APIs. Not a complete solution.
- Implement and perform bounds checking on input.
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Other vulnerabilities in SIMATIC PCS neo V4.1
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
- 8.2 High severity
- 9.8 Critical severity
- 7.5 High severity
Recent Stack-based Buffer Overflow vulnerabilities
- 7.5 High severity
- 7.5 High severity
- 9.8 Critical severity
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
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