Security readout for executives and security teams
Plain-English summary
This affects Siemens building automation controllers and Nucleus networking code that parse DNS responses. A malicious DNS response from a privileged network position could crash the device process or potentially run code. The business concern is disruption or compromise of building-control environments where affected APOGEE, TALON, or Nucleus-based systems remain unpatched.
Executive priority
Treat as high priority for building automation and embedded-networking environments, especially where affected controllers support critical facilities. The issue is not described as actively exploited, but the possible impact includes service outage and code execution.
Technical view
The vulnerable DNS name decompression code fails to validate pointer offset values, causing a write past an allocated structure when malformed responses are parsed. Siemens lists affected APOGEE PXC, TALON TC, Nucleus NET before V5.2, and Nucleus source code using affected DNS modules. CVSS 3.1 is 8.1 with high complexity and no user interaction.
Likely exposure
Exposure is most likely in operational technology, building automation, or embedded products using the listed Siemens APOGEE, TALON, or Nucleus networking components. Internet exposure is not stated in the sources; prioritize internal networks where attackers could influence DNS responses.
Exploitation context
The sources state exploitation requires a privileged network position and malformed DNS responses. The provided data does not show CISA KEV listing or confirmed active exploitation. Impact may include code execution in the current process or denial of service.
Researcher notes
Key constraints are high attack complexity and a privileged network position. Focus validation on affected DNS modules, version provenance, and network paths for DNS response manipulation. Do not assume exposure beyond the Siemens-listed products and Nucleus-derived code without asset evidence.
Mitigation direction
- Upgrade APOGEE BACnet and TALON BACnet products to V3.5.5 or later.
- Upgrade APOGEE P2 Ethernet products to V2.8.20 or later.
- Upgrade Nucleus NET to V5.2 or later where applicable.
- Review Siemens advisories for product-specific update and deployment guidance.
- Segment building automation networks from untrusted DNS and user networks.
Validation and detection
- Inventory Siemens APOGEE PXC, TALON TC, Nucleus NET, and Nucleus source deployments.
- Confirm product versions meet or exceed the fixed versions named by Siemens.
- Identify embedded products built from Nucleus source code with affected DNS modules.
- Review DNS paths where an attacker could influence responses to affected devices.
- Track remediation evidence in OT asset and vulnerability management records.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-823: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCVE-2020-27009 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- High
- CVSS
- 8.1 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H/E:P/RL:O/RC:C
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H/E:P/RL:O/RC:C2.25.9Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
8.1HighVector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H/E:P/RL:O/RC:C
Source materials
- CVE List V5 sourceCVE List V5
- https://cert-portal.siemens.com/productcert/pdf/ssa-185699.pdfCVE reference
- https://cert-portal.siemens.com/productcert/pdf/ssa-180579.pdfCVE reference
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Use of Out-of-range Pointer Offset
Use of Out-of-range Pointer Offset represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.