Overview
CVE-2025-41691 represents a critical vulnerability that affects CODESYS Control runtime systems. An unauthenticated remote attacker can exploit this weakness to trigger a NULL pointer dereference by sending specially crafted communication requests. This can potentially result in a denial-of-service (DoS) condition, leading to a system compromise or data leakage. Therefore, it is of utmost importance to understand the vulnerability and apply the necessary mitigation measures.
Vulnerability Summary
CVE ID: CVE-2025-41691
Severity: High (7.5 CVSS Score)
Attack Vector: Network
Privileges Required: None
User Interaction: None
Impact: Denial of service, potential system compromise or data leakage
Affected Products
Escape the Surveillance Era
Most apps won’t tell you the truth.
They’re part of the problem.
Phone numbers. Emails. Profiles. Logs.
It’s all fuel for surveillance.
Ameeba Chat gives you a way out.
- • No phone number
- • No email
- • No personal info
- • Anonymous aliases
- • End-to-end encrypted
Chat without a trace.
Product | Affected Versions
CODESYS Control runtime systems | All prior versions
How the Exploit Works
The vulnerability is exploited when an unauthenticated attacker sends a specially crafted communication request to the CODESYS Control runtime systems. This malicious request triggers a NULL pointer dereference, which can cause the system to crash and lead to a denial-of-service condition. This exploit does not require any user interaction, which makes it even more dangerous.
Conceptual Example Code
Here’s a conceptual example of how the vulnerability might be exploited. This is a sample HTTP POST request, which includes a malicious payload.
POST /vulnerable/endpoint HTTP/1.1
Host: target.example.com
Content-Type: application/json
{ "malicious_payload": "{ 'trigger': 'NULL_pointer_dereference' }" }
Mitigation Measures
To mitigate this vulnerability, it is strongly advised to apply patches provided by the vendor. In the absence of a patch, or until it can be applied, using a Web Application Firewall (WAF) or Intrusion Detection System (IDS) can provide temporary mitigation. Regular monitoring and updating of systems are also recommended to prevent exploitation of the vulnerability.

