CVE-2025-40757 Overview
CVE-2025-40757 is an information disclosure vulnerability affecting Siemens building automation controllers. The flaw impacts the APOGEE PXC Series (BACnet), APOGEE PXC Series (P2 Ethernet), and TALON TC Series (BACnet) product lines. Affected devices connected to the network permit unrestricted access to sensitive files, including internal databases. An unauthenticated attacker can retrieve an encrypted .db file that contains password material. The weakness is classified under [CWE-200] Exposure of Sensitive Information to an Unauthorized Actor. Siemens documents the issue in advisory SSA-916339.
Critical Impact
Network-reachable APOGEE PXC and TALON TC controllers expose an encrypted password database to unauthenticated attackers, enabling offline credential recovery attempts against building automation systems.
Affected Products
- APOGEE PXC Series (BACnet) — all versions
- APOGEE PXC Series (P2 Ethernet) — all versions
- TALON TC Series (BACnet) — all versions
Discovery Timeline
- 2025-09-09 - CVE-2025-40757 published to NVD
- 2026-06-17 - Last updated in NVD database
Technical Details for CVE-2025-40757
Vulnerability Analysis
The vulnerability resides in the file access controls of affected APOGEE PXC and TALON TC controllers. The devices expose sensitive resources over the network without enforcing authentication or authorization. An attacker with network reachability to a controller can request internal database files directly. Among the retrievable artifacts is an encrypted .db file that stores account credentials. Once retrieved, the file can be subjected to offline cryptanalysis or brute force attempts to recover plaintext passwords. Successful recovery would let an attacker authenticate to the controller and manipulate building automation logic tied to heating, ventilation, cooling, and access systems. The exposure aligns with [CWE-200] and reflects a broader pattern in legacy operational technology (OT) devices where file services were designed without network-facing threat models. Exploitation requires no user interaction and no prior privileges, though the attacker must first reach the device over a routed or flat network segment. Siemens has not published a firmware fix; mitigation currently relies on network segmentation and access restriction as described in SSA-916339.
Root Cause
The controllers permit unrestricted file retrieval over their network services. Sensitive files, including the password database, are accessible without authentication controls that would normally gate such resources.
Attack Vector
The attack vector is network-based. An attacker on a routable path to the controller issues a file retrieval request and downloads the encrypted database. No credentials, user interaction, or physical access are required beyond network reachability.
No verified proof-of-concept code is available for this vulnerability. Refer to the Siemens advisory for authoritative technical details.
Detection Methods for CVE-2025-40757
Indicators of Compromise
- Unexpected outbound transfers of .db files or other database artifacts from APOGEE PXC or TALON TC controllers.
- Connection attempts to controller file services from hosts outside the engineering or building management VLAN.
- Repeated file retrieval requests from a single source targeting multiple controllers in sequence.
Detection Strategies
- Monitor network flows to and from BACnet and P2 Ethernet controllers for atypical file transfer volumes.
- Deploy passive OT network monitoring to baseline expected protocol behavior and flag deviations.
- Alert on any authentication or reconnaissance activity against building automation subnets from IT or guest networks.
Monitoring Recommendations
- Log all access attempts to controller management interfaces and forward logs to a centralized SIEM.
- Correlate controller access events with firewall and switch telemetry to identify unauthorized lateral movement.
- Review controller configurations periodically for signs of credential misuse or unexpected changes.
How to Mitigate CVE-2025-40757
Immediate Actions Required
- Isolate APOGEE PXC and TALON TC controllers on dedicated OT network segments with no direct internet exposure.
- Restrict access to controller file and management services using firewall rules that whitelist only engineering workstations.
- Rotate any credentials stored on affected devices, assuming the password database may have been retrieved.
- Review the Siemens advisory SSA-916339 for the latest vendor guidance.
Patch Information
Siemens has not published a firmware patch for the affected APOGEE PXC and TALON TC product lines as of the last NVD update on 2026-06-17. Consult SSA-916339 for updates on remediation status and any successor product recommendations.
Workarounds
- Place controllers behind a properly configured industrial firewall and block all inbound access from untrusted networks.
- Apply the defense-in-depth practices published in the Siemens Operational Guidelines for Industrial Security.
- Disable or restrict any unused network services on the controllers where configuration permits.
- Monitor controller network segments for anomalous file access patterns until a vendor fix is available.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
