CVE-2021-31345

Severity: critical (CVSS 9.1 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 1.6% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2021-11-09 · updated 2026-06-17
Weakness: CWE-1284

Description

A vulnerability has been identified in Capital Embedded AR Classic 431-422 (All versions), Capital Embedded AR Classic R20-11 (All versions < V2303), PLUSCONTROL 1st Gen (All versions). 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)

Affected products

Siemens Apogee Modular Building Controller Firmware: all versions
Siemens Apogee Modular Equiment Controller Firmware: all versions
Siemens Apogee Pxc Compact Firmware: all versions
Siemens Apogee Pxc Modular Firmware: all versions
Siemens Capital VSTAR: all versions
Siemens Nucleus NET: all versions
Siemens Nucleus ReadyStart V3: before 2014.12 — fixed in 2014.12
Siemens Nucleus Source Code: all versions
Siemens Talon Tc Compact Firmware: all versions
Siemens Talon Tc Modular Firmware: all versions

How to fix

Upgrade to a fixed version: Siemens Nucleus ReadyStart V3 2014.12. Check the vendor advisory for mitigations.

References

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