CVE-2026-102076: CWE-121: Stack-based Buffer Overflow in Siemens APOGEE MBC (PPC) (BACnet)

This vulnerability (CVE-2026-102076) is a stack-based buffer overflow (CWE-121) in Siemens APOGEE MBC (PPC) (BACnet), APOGEE MEC (PPC), APOGEE PXC Compact and Modular, and TALON TC products. The issue arises from improper validation of user-supplied input in the upload code functionality of the affected product web service. An unauthenticated remote attacker can exploit this flaw to cause a denial of service (application crash or service disruption). The vulnerability affects all versions of APOGEE MBC (PPC) (BACnet and P2 Ethernet), APOGEE MEC (PPC) (BACnet and P2 Ethernet), and TALON TC Modular (BACnet), and versions prior to 3.5.7 or 2.8.21 for APOGEE PXC Compact and Modular variants. The CVSS v3.1 score is 7.5, reflecting high severity due to network attack vector, no privileges required, no user interaction, and impact limited to availability.

An unauthenticated remote attacker can exploit this vulnerability to cause a denial of service by triggering a stack-based buffer overflow in the affected Siemens APOGEE and TALON products. The impact is limited to availability disruption; there is no confidentiality or integrity impact reported. No known exploits in the wild have been documented.

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Since no vendor patch or official fix is documented, users should monitor Siemens advisories for updates. Until a fix is available, restrict access to the affected product web services to trusted networks and consider implementing network-level protections to limit exposure.