CVE-2021-25663: Siemens Capital Vstar

High severity, CVSS 7.5. EPSS: 1.9% chance of exploitation in the next 30 days.

A vulnerability has been identified in Capital Embedded AR Classic 431-422 (All versions), Capital Embedded AR Classic R20-11 (All versions < V2303), Nucleus NET (All versions), Nucleus ReadyStart V3 (All versions < V2017.02.4), Nucleus ReadyStart V4 (All versions < V4.1.0), Nucleus Source Code (All versions including affected IPv6 stack). The function that processes IPv6 headers does not check the lengths of extension header options, allowing attackers to put this function into an infinite loop with crafted length values.

Affected products

• Siemens Capital Vstar: affected versions not specified
• Siemens Nucleus Net: any version
• Siemens Nucleus Readystart: before 4.1.0 (fixed in 4.1.0); before 2017.02.4 (fixed in 2017.02.4)
• Siemens Nucleus Source Code: affected versions not specified

Published 2021-04-22. Last modified 2026-06-17.