ICSA-21-350-06: Siemens Capital VSTAR

CISA's summary

Summary: Multiple vulnerabilities (also known as "NUCLEUS:13") have be identified in the Nucleus RTOS (real-time operating system) and reported in the Siemens Security Advisory SSA-044112: https://cert-portal.siemens.com/productcert/html/ssa-044112.html. Capital Embedded AR Classic uses an affected version of the Nucleus software and inherently contains several of these vulnerabilities. Siemens has released a new version for Capital Embedded AR Classic R20-11 and recommends to update to the latest version. Siemens is preparing further fix versions and recommends specific countermeasures for products where fixes are not, or not yet available.

Products, as the advisory lists them

DeSpy has not checked any unit, hardware revision or firmware.

Vulnerabilities in this advisory

• CVE-2021-31344 — CVE-2021-31344 · CWE-843

  ICMP echo packets with fake IP options allow sending ICMP echo reply messages to arbitrary hosts on the network. (FSMD-2021-0004)

• CVE-2021-31345 — CVE-2021-31345 · CWE-1284

  The total length of an UDP payload (set in the IP header) is unchecked. This may lead to various side effects, including Information Leak and Denial-of-Service conditions, depending on a user-defined applications that runs on top of the UDP protocol. (FSMD-2021-0006)

• CVE-2021-31346 — CVE-2021-31346 · CWE-1284

  The total length of an ICMP payload (set in the IP header) is unchecked. This may lead to various side effects, including Information Leak and Denial-of-Service conditions, depending on the network buffer organization in memory. (FSMD-2021-0007)

• CVE-2021-31881 — CVE-2021-31881 · CWE-125

  When processing a DHCP OFFER message, the DHCP client application does not validate the length of the Vendor option(s), leading to Denial-of-Service conditions. (FSMD-2021-0008)

• CVE-2021-31882 — CVE-2021-31882 · CWE-119

  The DHCP client application does not validate the length of the Domain Name Server IP option(s) (0x06) when processing DHCP ACK packets. This may lead to Denial-of-Service conditions. (FSMD-2021-0011)

• CVE-2021-31883 — CVE-2021-31883 · CWE-119

  When processing a DHCP ACK message, the DHCP client application does not validate the length of the Vendor option(s), leading to Denial-of-Service conditions. (FSMD-2021-0013)

• CVE-2021-31889 — CVE-2021-31889 · CWE-191

  Malformed TCP packets with a corrupted SACK option leads to Information Leaks and Denial-of-Service conditions. (FSMD-2021-0015)

• CVE-2021-31890 — CVE-2021-31890 · CWE-240

  The total length of an TCP payload (set in the IP header) is unchecked. This may lead to various side effects, including Information Leak and Denial-of-Service conditions, depending on the network buffer organization in memory. (FSMD-2021-0017)

Acknowledgments, as the advisory lists them

• Siemens ProductCERT: reporting these vulnerabilities to CISA.

The advisory's legal notice

The use of Siemens Security Advisories is subject to the terms and conditions listed on: https://www.siemens.com/productcert/terms-of-use.

Sources

• The advisory at cisa.gov
• The CSAF document (JSON)

DeSpy's copy of this version is dated 2026-09-28.