CVE-2025-40833 Null Pointer Dereference in Affected Devices Leads to Denial of Service

CVE-2025-40833 describes a null pointer dereference vulnerability affecting certain devices. The vulnerability is triggered when processing specially crafted IPv4 requests. An unauthenticated, remote attacker can exploit this flaw to cause a denial-of-service (DoS) condition on the affected device. Successful exploitation requires a manual restart of the device to restore functionality. Siemens AG reported this vulnerability. The affected product list is not specified in the NVD or Siemens advisory.

Attack Chain

1. The attacker identifies a target device that is vulnerable to CVE-2025-40833.
2. The attacker crafts a malicious IPv4 request specifically designed to trigger the null pointer dereference.
3. The attacker sends the crafted IPv4 request to the targeted device.
4. The vulnerable code within the device attempts to process the malicious IPv4 request.
5. Due to the crafted nature of the request, a null pointer is dereferenced during processing.
6. This null pointer dereference causes the device to crash or become unresponsive.
7. The device enters a denial-of-service (DoS) state.
8. System administrators must manually restart the device to restore normal operation.

Impact

Successful exploitation of CVE-2025-40833 results in a denial-of-service condition. This can disrupt critical services provided by the affected device. The device becomes unresponsive, requiring a manual restart to recover. The specific number of affected devices and the sectors they belong to are unknown.

Recommendation

• Identify potentially vulnerable assets by cross-referencing internal asset lists with the Siemens security advisory linked in the references.
• Monitor network traffic for suspicious or malformed IPv4 requests targeting potentially vulnerable devices. Deploy the Sigma rule provided to detect potential exploitation attempts.
• Investigate and validate the patch provided by Siemens as detailed in the reference link to remediate the vulnerability.
• Consider implementing rate limiting on IPv4 traffic to potentially mitigate the impact of a DoS attack.