ICSA-21-257-07: Siemens APOGEE and TALON
CISA advisory · released 2021-09-14
Source record Collected from CISA's CSAF advisory feed
- Distribution label in the document: TLP:WHITE
- Revision 2, 2025-05-06 (final)
CISA's summary
Summary: A buffer overflow vulnerability in the integrated web server of multiple APOGEE and TALON automation devices could allow a remote attacker to execute arbitrary code on the devices with root privileges. Affected devices include the APOGEE MBC/MEC/PXC P2 Ethernet devices with Power Open Processors (PPC), APOGEE PXC BACnet devices, and TALON TC BACnet devices. Siemens has released updates for several affected products and recommends to update to the latest versions. Siemens recommends countermeasures for products where updates are not, or not yet available.
Products, as the advisory lists them
| Vendor | Product | Version |
|---|---|---|
| Siemens | APOGEE MBC (PPC) (P2 Ethernet) | >=V2.6.3 |
| Siemens | APOGEE MEC (PPC) (P2 Ethernet) | >=V2.6.3 |
| Siemens | APOGEE PXC Compact (BACnet) | <V3.5.3 |
| Siemens | APOGEE PXC Compact (P2 Ethernet) | >=V2.8 |
| Siemens | APOGEE PXC Modular (BACnet) | <V3.5.3 |
| Siemens | APOGEE PXC Modular (P2 Ethernet) | >=V2.8 |
| Siemens | TALON TC Compact (BACnet) | <V3.5.3 |
| Siemens | TALON TC Modular (BACnet) | <V3.5.3 |
DeSpy has not checked any unit, hardware revision or firmware.
Vulnerabilities in this advisory
- CVE-2021-27391 — CVE-2021-27391 · CWE-120
The web server of affected devices lacks proper bounds checking when parsing the Host parameter in HTTP requests, which could lead to a buffer overflow. An unauthenticated remote attacker could exploit this vulnerability to execute arbitrary code on the device with root privileges.
Acknowledgments, as the advisory lists them
- Siemens ProductCERT: reporting this vulnerability to CISA.
- Paul Noalhyt, David Doggett, Red Balloon Security: coordinated disclosure
The advisory's legal notice
Siemens Security Advisories are subject to the terms and conditions contained in Siemens' underlying license terms or other applicable agreements previously agreed to with Siemens (hereinafter "License Terms"). To the extent applicable to information, software or documentation made available in or through a Siemens Security Advisory, the Terms of Use of Siemens' Global Website (https://www.siemens.com/terms_of_use, hereinafter "Terms of Use"), in particular Sections 8-10 of the Terms of Use, shall apply additionally. In case of conflicts, the License Terms shall prevail over the Terms of Use.
Sources
DeSpy's copy of this version is dated 2026-09-28.
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