CVE-2025-41769 Overview
CVE-2025-41769 is a buffer overflow vulnerability [CWE-120] affecting the PROFINET service in Phoenix Contact devices under their default configuration. An unauthenticated remote attacker can exploit the flaw over the network to reboot the device or execute arbitrary code. The issue carries a CVSS v4.0 base score of 9.3 and requires no privileges or user interaction, making it a network-reachable pre-authentication threat to industrial control environments.
Critical Impact
Unauthenticated remote attackers can trigger device reboots or achieve arbitrary code execution on PROFINET-enabled devices via the network.
Affected Products
- Phoenix Contact devices exposing the PROFINET service in default configuration (see vendor advisory VDE-2025-056 for the full affected product matrix)
Discovery Timeline
- 2026-08-12 - CVE-2025-41769 published to NVD
- 2026-08-12 - Last updated in NVD database
Technical Details for CVE-2025-41769
Vulnerability Analysis
The vulnerability resides in the PROFINET service used by affected Phoenix Contact devices. PROFINET is an industrial Ethernet protocol used for real-time data exchange between controllers and field devices in operational technology (OT) networks. The service fails to properly validate the size of incoming data before writing it into a fixed-length buffer, producing a classic buffer overflow condition classified under [CWE-120].
Successful exploitation results in memory corruption. In the least severe case, corrupted memory forces the device to reboot, causing a denial-of-service condition on the industrial process. In the worst case, an attacker can overwrite control data structures to hijack execution flow and run arbitrary code within the device firmware context.
Root Cause
The root cause is missing or insufficient bounds checking on PROFINET protocol input handled by the device's network stack. Because the flaw is exposed in the default configuration, devices are vulnerable out of the box without any misconfiguration by the operator.
Attack Vector
The attack vector is network-based. An adversary with reachability to the PROFINET service (UDP/TCP ports used by PROFINET, typically on the OT LAN) sends a crafted protocol frame that overflows the target buffer. No authentication or user interaction is required. In flat or poorly segmented industrial networks, any compromised engineering workstation, HMI, or IT-to-OT pivot point provides sufficient adjacency to reach vulnerable devices.
No public proof-of-concept exploit has been observed, and the vulnerability is not listed in the CISA Known Exploited Vulnerabilities catalog at the time of writing.
Detection Methods for CVE-2025-41769
Indicators of Compromise
- Unexpected reboots or watchdog resets on Phoenix Contact PROFINET devices without a corresponding operator action
- Malformed or oversized PROFINET DCP/RPC frames captured on the OT network
- New or unexpected source hosts communicating with PROFINET endpoints outside of engineering windows
Detection Strategies
- Deploy OT-aware network intrusion detection (for example, protocol-aware IDS) with signatures for anomalous PROFINET frame lengths and malformed DCP identify/set requests
- Baseline normal PROFINET talkers and alert on any new source MAC or IP addressing PROFINET services
- Correlate device reboot events from controller logs with concurrent PROFINET traffic anomalies
Monitoring Recommendations
- Continuously monitor the OT/IT boundary for east-west traffic reaching PROFINET services from unauthorized zones
- Forward device syslog and controller diagnostic buffers to a centralized SIEM for cross-device correlation of reboot storms
- Track firmware version inventory to identify unpatched devices as vendor updates become available
How to Mitigate CVE-2025-41769
Immediate Actions Required
- Consult the Phoenix Contact Security Advisory VDE-2025-056 to identify affected product families and firmware versions in your environment
- Restrict network reachability to the PROFINET service so that only known engineering stations and controllers can communicate with affected devices
- Enforce strict segmentation between IT and OT networks using firewalls or unidirectional gateways
Patch Information
Refer to the Phoenix Contact Security Advisory VDE-2025-056 for firmware updates, fixed versions, and vendor-recommended hardening steps. Apply firmware updates during scheduled maintenance windows and validate device operation after patching.
Workarounds
- Place vulnerable devices behind an industrial firewall that filters PROFINET traffic by source address and frame characteristics
- Disable the PROFINET service on devices where it is not required for the process
- Apply the vendor's recommended non-default hardening configuration where firmware updates cannot be immediately deployed
# Example: restrict PROFINET reachability at an upstream firewall
# Allow PROFINET DCP/RT only from authorized engineering VLAN to device VLAN
# and drop all other sources by default.
iptables -A FORWARD -s 10.20.10.0/24 -d 10.30.40.0/24 -p udp --dport 34964 -j ACCEPT
iptables -A FORWARD -d 10.30.40.0/24 -p udp --dport 34964 -j DROP
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
