ICSA-21-103-04: Siemens Nucleus Products DNS Module (Update A)
CISA advisory · released 2021-04-13
Source record Collected from CISA's CSAF advisory feed
- Distribution label in the document: TLP:WHITE
- Revision 4, 2025-05-06 (final)
CISA's summary
Summary: Security researchers discovered and disclosed 9 vulnerabilities in several DNS implementations, also known as “NAME:WRECK” vulnerabilities. The vulnerabilities described in this advisory are from this set. The DNS client of the networking component (Nucleus NET) in Nucleus Real-Time Operating System (RTOS) contains two out of bounds write vulnerabilities in the handling of DNS responses that could allow an attacker to cause a denial-of-service condition or to remotely execute code. Siemens has released updates for several affected products and recommends to update to the latest versions. Siemens recommends specific countermeasures for products where updates are not available.
Products, as the advisory lists them
| Vendor | Product | Version |
|---|---|---|
| Siemens | Nucleus NET | <V5.2 |
| Siemens | Nucleus Source Code | including_affected_DNS_modules |
DeSpy has not checked any unit, hardware revision or firmware.
Vulnerabilities in this advisory
- CVE-2020-15795 — CVE-2020-15795 · CWE-787
The DNS domain name label parsing functionality does not properly validate the names in DNS-responses. The parsing of malformed responses could result in a write past the end of an allocated structure. An attacker with a privileged position in the network could leverage this vulnerability to execute code in the context of the current process or cause a denial-of-service condition.
- CVE-2020-27009 — CVE-2020-27009 · CWE-823
The DNS domain name record decompression functionality does not properly validate the pointer offset values. The parsing of malformed responses could result in a write past the end of an allocated structure. An attacker with a privileged position in the network could leverage this vulnerability to execute code in the context of the current process or cause a denial-of-service condition.
Acknowledgments, as the advisory lists them
- Daniel dos Santos, Forescout Technologies Inc.: coordinated disclosure
The advisory's legal notice
Siemens Security Advisories are subject to the terms and conditions contained in Siemens' underlying license terms or other applicable agreements previously agreed to with Siemens (hereinafter "License Terms"). To the extent applicable to information, software or documentation made available in or through a Siemens Security Advisory, the Terms of Use of Siemens' Global Website (https://www.siemens.com/terms_of_use, hereinafter "Terms of Use"), in particular Sections 8-10 of the Terms of Use, shall apply additionally. In case of conflicts, the License Terms shall prevail over the Terms of Use.
Sources
DeSpy's copy of this version is dated 2026-09-28.
This product uses the NVD API but is not endorsed or certified by the NVD.
CVE records: Copyright © 1999-2026, The MITRE Corporation. CVE is a trademark and the CVE logo is a registered trademark of The MITRE Corporation.
CVE Usage: MITRE hereby grants you a perpetual, worldwide, non-exclusive, no-charge, royalty-free, irrevocable copyright license to reproduce, prepare derivative works of, publicly display, publicly perform, sublicense, and distribute Common Vulnerabilities and Exposures (CVE™). Any copy you make for such purposes is authorized provided that you reproduce MITRE's copyright designation and this license in any such copy.
CISA's Known Exploited Vulnerabilities catalog and CISA Vulnrichment data are CC0 1.0. CISA advisories are shown with the TLP label their document carries. No endorsement by CISA, DHS, NIST or MITRE is stated or implied.