What is CVE-2021-27393?

CVE-2021-27393 is a vulnerability identified in Nucleus NET, Nucleus ReadyStart V3, and Nucleus Source Code that allows an attacker to poison the DNS client by not properly randomizing UDP port numbers of DNS requests.

What is the severity of CVE-2021-27393?

The severity of CVE-2021-27393 is medium with a CVSS v3.1 base score of 5.3.

Which software is affected by CVE-2021-27393?

CVE-2021-27393 affects Siemens Nucleus NET, Siemens Nucleus ReadyStart V3 (versions earlier than V2013.08), and Siemens Nucleus Source Code (versions including affected DNS modules).

How can an attacker exploit CVE-2021-27393?

An attacker can exploit CVE-2021-27393 by manipulating DNS requests and poisoning the DNS client.

Is there a fix available for CVE-2021-27393?

Yes, Siemens has provided a fix for CVE-2021-27393. Please refer to the vendor's security advisory for more information.

Vulnerability/
CVE-2021-27393

medium

5.3

CWE

330

22/4/2021

3/8/2024

CVE-2021-27393

First published: Thu Apr 22 2021(Updated: )

A vulnerability has been identified in Nucleus NET (All versions), Nucleus ReadyStart V3 (All versions < V2013.08), Nucleus Source Code (Versions including affected DNS modules). The DNS client does not properly randomize UDP port numbers of DNS requests. That could allow an attacker to poison the DNS cache or spoof DNS resolving.

Credit: productcert@siemens.com

Affected Software	Affected Version	How to fix
Siemens Nucleus NET
Siemens Nucleus ReadyStart v3	<2013.08
Siemens Nucleus Source Code

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Reference Links

https://cert-portal.siemens.com/productcert/pdf/ssa-201384.pdf

Frequently Asked Questions

What is CVE-2021-27393?
CVE-2021-27393 is a vulnerability identified in Nucleus NET, Nucleus ReadyStart V3, and Nucleus Source Code that allows an attacker to poison the DNS client by not properly randomizing UDP port numbers of DNS requests.
What is the severity of CVE-2021-27393?
The severity of CVE-2021-27393 is medium with a CVSS v3.1 base score of 5.3.
Which software is affected by CVE-2021-27393?
CVE-2021-27393 affects Siemens Nucleus NET, Siemens Nucleus ReadyStart V3 (versions earlier than V2013.08), and Siemens Nucleus Source Code (versions including affected DNS modules).
How can an attacker exploit CVE-2021-27393?
An attacker can exploit CVE-2021-27393 by manipulating DNS requests and poisoning the DNS client.
Is there a fix available for CVE-2021-27393?
Yes, Siemens has provided a fix for CVE-2021-27393. Please refer to the vendor's security advisory for more information.

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canonical/siemens nucleus source code

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