How severe is CVE-2021-31881?

CVE-2021-31881 has a CVSS 3.x base score of 7.1, rated high severity. It is exploitable over an adjacent network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is low, integrity none, and availability high.

Is CVE-2021-31881 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (71st percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-31881?

CVE-2021-31881 primarily affects Siemens Capital Vstar. In total, 10 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-31881?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2021-31881 published?

CVE-2021-31881 was published on 2021-11-09 and last updated on 2026-06-17.

CVE-2021-31881

CVE-2021-31881 is a high-severity vulnerability in Siemens Capital Vstar with a CVSS 3.x base score of 7.1. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-125.

Key facts

Severity: High (CVSS 3.x base score 7.1)
CVSS v2: 5.0
EPSS exploit prediction: 1% (71st percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-125
Affected product: Siemens Capital Vstar
Published: 2021-11-09
Last modified: 2026-06-17

Description

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)

Frequently asked questions

What is CVE-2021-31881?: 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)
How severe is CVE-2021-31881?: CVE-2021-31881 has a CVSS 3.x base score of 7.1, rated high severity. It is exploitable over an adjacent network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is low, integrity none, and availability high.
Is CVE-2021-31881 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (71st percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-31881?: CVE-2021-31881 primarily affects Siemens Capital Vstar. In total, 10 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-31881?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2021-31881 published?: CVE-2021-31881 was published on 2021-11-09 and last updated on 2026-06-17.

References

Affected products (10)

cpe:2.3:a:siemens:capital_vstar:*:*:*:*:*:*:*:*
cpe:2.3:a:siemens:nucleus_net:*:*:*:*:*:*:*:*
cpe:2.3:a:siemens:nucleus_readystart_v3:*:*:*:*:*:*:*:*
cpe:2.3:a:siemens:nucleus_source_code:*:*:*:*:*:*:*:*
cpe:2.3:o:siemens:apogee_modular_building_controller_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:siemens:apogee_modular_equiment_controller_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:siemens:apogee_pxc_compact_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:siemens:apogee_pxc_modular_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:siemens:talon_tc_compact_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:siemens:talon_tc_modular_firmware:*:*:*:*:*:*:*:*

More vulnerabilities in Siemens Capital Vstar

CVE-2021-31884 — Critical (CVSS 9.8): A vulnerability has been identified in APOGEE MBC (PPC) (BACnet) (All versions), APOGEE MBC (PPC) (P2 Ethernet) (All…
CVE-2021-31346 — High (CVSS 8.2): A vulnerability has been identified in Capital Embedded AR Classic 431-422 (All versions), Capital Embedded AR Classic…
CVE-2021-31890 — High (CVSS 7.5): A vulnerability has been identified in Capital Embedded AR Classic 431-422 (All versions), Capital Embedded AR Classic…
CVE-2021-31889 — High (CVSS 7.5): A vulnerability has been identified in Capital Embedded AR Classic 431-422 (All versions), Capital Embedded AR Classic…
CVE-2021-31885 — High (CVSS 7.5): A vulnerability has been identified in APOGEE MBC (PPC) (BACnet) (All versions), APOGEE MBC (PPC) (P2 Ethernet) (All…
CVE-2021-31345 — High (CVSS 7.5): A vulnerability has been identified in Capital Embedded AR Classic 431-422 (All versions), Capital Embedded AR Classic…

All CVEs affecting Siemens Capital Vstar →

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CVE-2021-21777 — Critical (CVSS 10.0): An information disclosure vulnerability exists in the Ethernet/IP UDP handler functionality of EIP Stack Group OpENer…
CVE-2017-14451 — Critical (CVSS 10.0): An exploitable out-of-bounds read vulnerability exists in libevm (Ethereum Virtual Machine) of CPP-Ethereum. A…
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