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No exploitation reportedFix available

CVE-2020-27009

No exploitation reported by the sources we read.

  • Published2021-04-22
  • Fixed in5.2
  • WeaknessCWE-787 · CWE-823

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

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.

Timeline

dates in UTC
  1. 2021-04-2221:15CVE publishedNVD

Observed activity

isMalicious corpus · updated 2026-10-23 18:48 UTC
Indicators tagged with this CVE, per day0 indicators over 7 days
Block these indicators
  • Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2020-27009?format=txt
  • CSV export: https://api.ismalicious.com/edl/cve/CVE-2020-27009?format=csv
  • TAXII collection of exploited CVEs
  • The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD
Siemens nucleus net
BranchAffectedFixed in
5.2< 5.25.2
Siemens nucleus source code
BranchAffectedFixed in
—all versionsno fix published

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Distribution builds and vendor advisories

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Vendor advisories

  • ICSA-22-349-16 CISA6 known affected

    Siemens APOGEE and TALON

    APOGEE PXC Compact (BACnet) · APOGEE PXC Compact (P2 Ethernet) · APOGEE PXC Modular (BACnet) · +3 more

  • ICSA-21-103-04 CISA2 known affected

    Siemens Nucleus Products DNS Module (Update A)

    Nucleus NET · Nucleus Source Code

Full record on NVD

Fix

  1. Update Siemens nucleus net to 5.2
  2. Vendor fix CISA ICSA-22-349-16 · 2 productsUpdate to V2.8.20 or later version
  3. Vendor fix CISA ICSA-22-349-16 · 4 productsUpdate to V3.5.5 or later version
  4. Vendor fix CISA ICSA-21-103-04 · 1 productContact customer support to receive patch and update information
  5. Workaround from the vendor CISA ICSA-21-103-04 · 2 productsAvoid using DNS client of affected versions
  6. Mitigation from the vendor CISA ICSA-21-103-04 · 1 productUpdate to the latest version of Nucleus ReadyStart V3 or V4
  7. Mitigation from the vendor CISA ICSA-21-103-04 · 1 productNote that the latest version of Nucleus NET (V5.2) is not affected, but is already beyond end of software support

Advisories and patches

Detection

Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof-of-concept repositories
none listed
PoC-in-GitHub

Sources

  • CNACVSS 3.18.1read 2026-10-23
  • NVDCVSS 3.18.1read 2026-10-23
  • NVDCVSS 2.06.8read 2026-10-23
  • CNAweakness (CWE)CWE-823read 2026-10-23
  • NVDweakness (CWE)CWE-787read 2026-10-23
  • FIRST EPSSEPSS score7.2 %2026-10-22

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Published
2021-04-22
Last Modified
2026-06-17
NVD status
Modified

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.

Is CVE-2020-27009 actively exploited?

Active exploitation of CVE-2020-27009 has not been confirmed. Its EPSS score was 7.2% on 2026-10-22, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2020-27009?

CVE-2020-27009 has a CVSS v3 base score of 8.1 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H.

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