How severe is CVE-2020-27009?

CVE-2020-27009 has a CVSS 3.x base score of 8.1, rated high severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2020-27009 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 7% (94th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2020-27009?

CVE-2020-27009 primarily affects Siemens Nucleus Net. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2020-27009?

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-2020-27009 published?

CVE-2020-27009 was published on 2021-04-22 and last updated on 2026-06-17.

CVE-2020-27009

CVE-2020-27009 is a high-severity vulnerability in Siemens Nucleus Net with a CVSS 3.x base score of 8.1. 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-787.

Key facts

Severity: High (CVSS 3.x base score 8.1)
CVSS v2: 6.8
EPSS exploit prediction: 7% (94th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-787
Affected product: Siemens Nucleus Net
Published: 2021-04-22
Last modified: 2026-06-17

Description

A vulnerability has been identified in APOGEE PXC Compact (BACnet) (All versions < V3.5.5), APOGEE PXC Compact (P2 Ethernet) (All versions < V2.8.20), APOGEE PXC Modular (BACnet) (All versions < V3.5.5), APOGEE PXC Modular (P2 Ethernet) (All versions < V2.8.20), Nucleus NET (All versions < V5.2), Nucleus Source Code (Versions including affected DNS modules), TALON TC Compact (BACnet) (All versions < V3.5.5), TALON TC Modular (BACnet) (All versions < V3.5.5). The DNS domain name record decompression functionality does not properly validate the pointer offset values. The parsing of malformed responses could result in a write past the end of an allocated structure. An attacker with a privileged position in the network could leverage this vulnerability to execute code in the context of the current process or cause a denial-of-service condition.

Frequently asked questions

What is CVE-2020-27009?: A vulnerability has been identified in APOGEE PXC Compact (BACnet) (All versions < V3.5.5), APOGEE PXC Compact (P2 Ethernet) (All versions < V2.8.20), APOGEE PXC Modular (BACnet) (All versions < V3.5.5), APOGEE PXC Modular (P2 Ethernet) (All versions < V2.8.20), Nucleus NET (All versions < V5.2), Nucleus Source Code (Versions including affected DNS modules), TALON TC Compact (BACnet) (All versions < V3.5.5), TALON TC Modular (BACnet) (All versions < V3.5.5). The DNS domain name record decompression functionality does not properly validate the pointer offset values. The parsing of malformed responses could result in a write past the end of an allocated structure. An attacker with a privileged position in the network could leverage this vulnerability to execute code in the context of the current process or cause a denial-of-service condition.
How severe is CVE-2020-27009?: CVE-2020-27009 has a CVSS 3.x base score of 8.1, rated high severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2020-27009 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 7% (94th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2020-27009?: CVE-2020-27009 primarily affects Siemens Nucleus Net. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2020-27009?: 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-2020-27009 published?: CVE-2020-27009 was published on 2021-04-22 and last updated on 2026-06-17.

References

Affected products (2)

cpe:2.3:a:siemens:nucleus_net:*:*:*:*:*:*:*:*
cpe:2.3:a:siemens:nucleus_source_code:-:*:*:*:*:*:*:*

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