Control RTE (SL): NULL Pointer Dereference
CVE-2025-41691 is a high-severity NULL pointer dereference vulnerability in Control RTE (SL) from Codesys, with a CVSS 3.1 base score of 7.5 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists version 3.5.21.20 as the first without the flaw, so updating Control RTE (SL) to that release or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.64% chance of exploitation within 30 days, higher than 51% of scored CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update Control RTE (SL) to 3.5.21.20 or a later version.
- Update Control RTE (for Beckhoff CX) SL to 3.5.21.20 or a later version.
- Update Control Win (SL) to 3.5.21.20 or a later version.
- 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 |
|---|---|---|---|
| CODESYS | Control RTE (SL) | 3.5.21.10 up to, but not including, 3.5.21.20 | 3.5.21.20 |
| CODESYS | Control RTE (for Beckhoff CX) SL | 3.5.21.10 up to, but not including, 3.5.21.20 | 3.5.21.20 |
| CODESYS | Control Win (SL) | 3.5.21.10 up to, but not including, 3.5.21.20 | 3.5.21.20 |
| CODESYS | HMI (SL) | 3.5.21.10 up to, but not including, 3.5.21.20 | 3.5.21.20 |
| CODESYS | Control for BeagleBone SL | 4.16.0.0 up to, but not including, 4.17.0.0 | 4.17.0.0 |
| CODESYS | Control for emPC-A/iMX6 SL | 4.16.0.0 up to, but not including, 4.17.0.0 | 4.17.0.0 |
| CODESYS | Control for IOT2000 SL | 4.16.0.0 up to, but not including, 4.17.0.0 | 4.17.0.0 |
| CODESYS | Control for Linux ARM SL | 4.16.0.0 up to, but not including, 4.17.0.0 | 4.17.0.0 |
| CODESYS | Control for Linux SL | 4.16.0.0 up to, but not including, 4.17.0.0 | 4.17.0.0 |
| CODESYS | Control for PFC100 SL | 4.16.0.0 up to, but not including, 4.17.0.0 | 4.17.0.0 |
| CODESYS | Control for PFC200 SL | 4.16.0.0 up to, but not including, 4.17.0.0 | 4.17.0.0 |
| CODESYS | Control for PLCnext SL | 4.16.0.0 up to, but not including, 4.17.0.0 | 4.17.0.0 |
| CODESYS | Control for Raspberry Pi SL | 4.16.0.0 up to, but not including, 4.17.0.0 | 4.17.0.0 |
| CODESYS | Control for WAGO Touch Panels 600 SL | 4.16.0.0 up to, but not including, 4.17.0.0 | 4.17.0.0 |
| CODESYS | Virtual Control SL | 4.16.0.0 up to, but not including, 4.17.0.0 | 4.17.0.0 |
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
- NoneNo data is disclosed.
- Integrity
- NoneNothing can be modified.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H. Scored by CNA (cert.vde.com).
Official description
An unauthenticated remote attacker may trigger a NULL pointer dereference in the affected CODESYS Control runtime systems by sending specially crafted communication requests, potentially leading to a denial-of-service (DoS) condition.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: NULL Pointer Dereference
The product dereferences a pointer that it expects to be valid but is NULL.
How developers prevent this class of flaw
- For any pointers that could have been modified or provided from a function that can return NULL, check the pointer for NULL before use. When working with a multithreaded or otherwise asynchronous environment, ensure that proper locking APIs are used to lock before the check, and unlock when it has finished.
- Select a programming language that is not susceptible to these issues.
- Check the results of all functions that return a value and verify that the value is non-null before acting upon it.
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: yes, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Other references
Other vulnerabilities in Control RTE (SL)
- 8.1 High severity
- 7.5 High severity
- 8.3 High severity
- 7.5 High severity
- 8.8 High severity
- 7.5 High severity
Recent NULL Pointer Dereference vulnerabilities
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
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