WAGO BACnet IP Stack: Path traversal in dynamically created BACnet File Objects
Summary
Several WAGO controller and communication devices running firmware below 4.8.9 are affected. The object name of dynamically created BACnet File Objects is used as a file path without sufficient validation, so relative paths can leave the intended directory. An unauthenticated remote attacker with network access to the BACnet service can read or overwrite arbitrary files on the device, which may lead to full system compromise or service disruption.
Affected
- WAGO devices in multiple families (e.g. 0751-9x01, 0750-811x-xxxx-xxxx, 0750-821x-xxx-xxx, 0762-420x-8000-000x, 0762-630x-8000-000x, 0752-8303-8000-0002, 0762-340x)
- Firmware (wago_os_linux) 1.0.0 to below 4.8.9 (FW30 and custom 70 builds)
- Full model list: see vendor advisory; sources differ, so verify against VDE-2025-102
Fixed in
- Firmware 4.8.9 (FW30) or higher, per the vendor remediation
- Custom firmware builds: contact WAGO support for the fixed version
- Unknown: whether 4.10.0 (FW32) is the designated fix for this CVE
Workaround
- No vendor workaround known.
- Restrict BACnet/IP (typically UDP) to the building automation network.
- Block BACnet access from the internet and untrusted networks.
- Disable BACnet services that are not required.
Exploitation
- CISA SSVC: exploitation none, automatable yes, technical impact total.
- Not listed as known exploited (KEV).
- No public proof of concept confirmed at the time of research.
Our recommendation
- Inventory all WAGO devices and their firmware versions, and check whether BACnet is active.
- Verify that no WAGO controller is reachable from the internet (remote maintenance, VPN shortcuts, port forwards).
- Segment or block BACnet traffic until the devices are patched.
- Schedule an update to the vendor-confirmed fixed version after testing with the integrator; ask WAGO which build to deploy.
- Monitor for vendor updates and exploit reports.
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- CERT@VDE Advisory VDE-2025-102 www.certvde.com
- VulnRichment CVE-2025-41753 vulners.com
- INCIBE-CERT Alert (WAGO) www.incibe.es
- CISA ICS Advisory ICSA-26-293-02 www.cisa.gov
- OpenCVE CVE-2025-41753 app.opencve.io
- ThreatIntel CVE-2025-41753 cve.threatint.com
Researched and written up in English and German by an AI (Claude by Anthropic) based on NVD, CISA, EPSS and the sources listed. The vendor information is authoritative. Researched on 31 Oct 2026, 03:43.
Original description (NVD)
The object name of a dynamically created BACnet File Object is interpreted as a file path without sufficient validation. Because relative paths are not limited to the intended directory, an unauthenticated remote attacker can traverse outside of it and read or overwrite arbitrary files on the device, which may lead to full system compromise.
NVD references (1)
Sources
The tracker combines official, freely usable data sources – updated continuously:
- NVD (NIST) – CVEs, rating (CVSS), affected products
- CISA KEV – vulnerabilities confirmed by CISA as actively exploited
- CISA Vulnrichment – CISA assessment (SSVC) in the official CVE record
- FIRST EPSS – probability of exploitation
- Microsoft MSRC – Patch Tuesday: vulnerabilities, severity, updates
- PoC-in-GitHub – public proof-of-concept repositories
- Metasploit (Rapid7) – modules of the Metasploit Framework
- Exploit-DB (OffSec) – archive of public exploits (links only)
- Patch days: official vendor pages (linked per vendor) (Vendor patch days)
This product uses data from the NVD API but is not endorsed or certified by the NVD. EPSS data © FIRST.org.
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