How severe is CVE-2021-31884?

CVE-2021-31884 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2021-31884 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (70th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-31884?

CVE-2021-31884 primarily affects Siemens Capital Vstar. In total, 23 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-31884?

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

When was CVE-2021-31884 published?

CVE-2021-31884 was published on 2021-11-09 and last updated on 2026-06-17.

CVE-2021-31884

CVE-2021-31884 is a critical-severity vulnerability in Siemens Capital Vstar with a CVSS 3.x base score of 9.8. 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-170.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
CVSS v2: 7.5
EPSS exploit prediction: 1% (70th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-170
Affected product: Siemens Capital Vstar
Published: 2021-11-09
Last modified: 2026-06-17

Description

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 < V3.5.4), APOGEE PXC Compact (P2 Ethernet) (All versions < V2.8.19), APOGEE PXC Modular (BACnet) (All versions < V3.5.4), APOGEE PXC Modular (P2 Ethernet) (All versions < V2.8.19), Capital VSTAR (All versions with enabled Ethernet options), Desigo PXC00-E.D (All versions >= V2.3 and < V6.30.016), Desigo PXC00-U (All versions >= V2.3 and < V6.30.016), Desigo PXC001-E.D (All versions >= V2.3 and < V6.30.016), Desigo PXC100-E.D (All versions >= V2.3 and < V6.30.016), Desigo PXC12-E.D (All versions >= V2.3 and < V6.30.016), Desigo PXC128-U (All versions >= V2.3 and < V6.30.016), Desigo PXC200-E.D (All versions >= V2.3 and < V6.30.016), Desigo PXC22-E.D (All versions >= V2.3 and < V6.30.016), Desigo PXC22.1-E.D (All versions >= V2.3 and < V6.30.016), Desigo PXC36.1-E.D (All versions >= V2.3 and < V6.30.016), Desigo PXC50-E.D (All versions >= V2.3 and < V6.30.016), Desigo PXC64-U (All versions >= V2.3 and < V6.30.016), Desigo PXM20-E (All versions >= V2.3 and < V6.30.016), Nucleus NET (All versions), Nucleus ReadyStart V3 (All versions < V2017.02.4), Nucleus Source Code (All versions), TALON TC Compact (BACnet) (All versions < V3.5.4), TALON TC Modular (BACnet) (All versions < V3.5.4). The DHCP client application assumes that the data supplied with the “Hostname” DHCP option is NULL terminated. In cases when global hostname variable is not defined, this may lead to Out-of-bound reads, writes, and Denial-of-service conditions. (FSMD-2021-0014)

Frequently asked questions

What is CVE-2021-31884?: 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 < V3.5.4), APOGEE PXC Compact (P2 Ethernet) (All versions < V2.8.19), APOGEE PXC Modular (BACnet) (All versions < V3.5.4), APOGEE PXC Modular (P2 Ethernet) (All versions < V2.8.19), Capital VSTAR (All versions with enabled Ethernet options), Desigo PXC00-E.D (All versions >= V2.3 and < V6.30.016), Desigo PXC00-U (All versions >= V2.3 and < V6.30.016), Desigo PXC001-E.D (All versions >= V2.3 and < V6.30.016), Desigo PXC100-E.D (All versions >= V2.3 and < V6.30.016), Desigo PXC12-E.D (All versions >= V2.3 and < V6.30.016), Desigo PXC128-U (All versions >= V2.3 and < V6.30.016), Desigo PXC200-E.D (All versions >= V2.3 and < V6.30.016), Desigo PXC22-E.D (All versions >= V2.3 and < V6.30.016), Desigo PXC22.1-E.D (All versions >= V2.3 and < V6.30.016), Desigo PXC36.1-E.D (All versions >= V2.3 and < V6.30.016), Desigo PXC50-E.D (All versions >= V2.3 and < V6.30.016), Desigo PXC64-U (All versions >= V2.3 and < V6.30.016), Desigo PXM20-E (All versions >= V2.3 and < V6.30.016), Nucleus NET (All versions), Nucleus ReadyStart V3 (All versions < V2017.02.4), Nucleus Source Code (All versions), TALON TC Compact (BACnet) (All versions < V3.5.4), TALON TC Modular (BACnet) (All versions < V3.5.4). The DHCP client application assumes that the data supplied with the “Hostname” DHCP option is NULL terminated. In cases when global hostname variable is not defined, this may lead to Out-of-bound reads, writes, and Denial-of-service conditions. (FSMD-2021-0014)
How severe is CVE-2021-31884?: CVE-2021-31884 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2021-31884 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (70th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-31884?: CVE-2021-31884 primarily affects Siemens Capital Vstar. In total, 23 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-31884?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2021-31884 published?: CVE-2021-31884 was published on 2021-11-09 and last updated on 2026-06-17.

References

Affected products (23)

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:*:*:*:*:*:*:*:*
cpe:2.3:o:siemens:desigo_pxc00-e.d_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:siemens:desigo_pxc00-u_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:siemens:desigo_pxc001-e.d_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:siemens:desigo_pxc12-e.d_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:siemens:desigo_pxc22-e.d_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:siemens:desigo_pxc22.1-e.d_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:siemens:desigo_pxc36.1-e.d_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:siemens:desigo_pxc50-e.d_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:siemens:desigo_pxc64-u_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:siemens:desigo_pxc100-e.d_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:siemens:desigo_pxc128-u_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:siemens:desigo_pxc200-e.d_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:siemens:desigo_pxm20-e_firmware:*:*:*:*:*:*:*:*

More vulnerabilities in Siemens Capital Vstar

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…
CVE-2021-25664 — 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 →

Other CWE-170 vulnerabilities

CVE-2021-1418 — Critical (CVSS 9.9): Multiple vulnerabilities in Cisco Jabber for Windows, Cisco Jabber for MacOS, and Cisco Jabber for mobile platforms…
CVE-2021-1417 — Critical (CVSS 9.9): Multiple vulnerabilities in Cisco Jabber for Windows, Cisco Jabber for MacOS, and Cisco Jabber for mobile platforms…
CVE-2021-1411 — Critical (CVSS 9.9): Multiple vulnerabilities in Cisco Jabber for Windows, Cisco Jabber for MacOS, and Cisco Jabber for mobile platforms…
CVE-2026-8721 — Critical (CVSS 9.8): Crypt::OpenSSL::PKCS12 versions through 1.94 for Perl truncates passwords with embedded NULLs. Password parameters in…
CVE-2021-31886 — Critical (CVSS 9.8): A vulnerability has been identified in APOGEE MBC (PPC) (BACnet) (All versions), APOGEE MBC (PPC) (P2 Ethernet) (All…
CVE-2019-8275 — Critical (CVSS 9.8): UltraVNC revision 1211 has multiple improper null termination vulnerabilities in VNC server code, which result in…

Browse all CWE-170 vulnerabilities →