CVE-2021-31881

A vulnerability has been identified in APOGEE MBC (PPC) (BACnet) (All versions), APOGEE MBC (PPC)...

7.1 High

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

Attack profile

How easy it is to exploit

Attack vector: Adjacent network
Complexity: Low
Privileges needed: None
User interaction: None

What an attacker can affect

Confidentiality: Low
Integrity: None
Availability: High

Exploit likelihood

1.53%Up 0.9 points since Nov 10, 2021

What each source reports

CVE List Score used 7.1

Record: CVE-2021-31881
CVSS 3.1: 7.1 HighCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H
Weakness: CWE-125
Updated: 2026-11-02

EUVDEUVD-2021-18756 7.1

Record: EUVD-2021-18756
CVSS 3.1: 7.1 HighCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H
Updated: 2026-11-02

GitHub AdvisoriesGHSA-x327-px9p-wgr2 7.5

A vulnerability has been identified in APOGEE MBC (PPC) (BACnet) (All versions), APOGEE MBC (PPC)...

A vulnerability has been identified in APOGEE MBC (PPC) (BACnet) (All versions), APOGEE MBC (PPC) (P2 Ethernet) (All versions), APOGEE MEC (PPC) (BACnet) (All versions), APOGEE MEC (PPC) (P2 Ethernet) (All versions), APOGEE PXC Compact (BACnet) (All versions), APOGEE PXC Compact (P2 Ethernet) (All versions), APOGEE PXC Modular (BACnet) (All versions), APOGEE PXC Modular (P2 Ethernet) (All versions), Capital VSTAR (All versions), Nucleus NET (All versions), Nucleus ReadyStart V3 (All versions < V2017.02.4), Nucleus Source Code (All versions), TALON TC Compact (BACnet) (All versions), TALON TC Modular (BACnet) (All versions). 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)

Record: GHSA-x327-px9p-wgr2
CVSS 3.1: 7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness: CWE-125
Updated: 2026-11-02

NVD 7.1

Record: CVE-2021-31881
CVSS 3.1: 7.1 HighCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H
CVSS 3.1: 7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CVSS 2.0: 5.0 MediumAV:N/AC:L/Au:N/C:N/I:N/A:P
Weakness: CWE-125
Updated: 2026-11-02

Affected products

History

History
Recorded	Changed	Sources
Nov 2, 2026	first indexed	CVE List, EUVD, GitHub Advisories, NVD

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2021-31881 is a high vulnerability (CVSS 7.1) in Siemens Capital Embedded Ar Classic 431-422, published November 9, 2021. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 1.53%, the 74th percentile. No source names a fixed version.