CVE-2025-41699: Web Management System RCE Vulnerability

CVE-2025-41699 Overview

CVE-2025-41699 is an authenticated code injection vulnerability affecting a Phoenix Contact device with a Web-based management interface. A low-privileged remote attacker with a valid management account can modify system configuration to inject commands that execute as root. Successful exploitation results in total loss of confidentiality, integrity, and availability on the affected device. The flaw is classified under [CWE-94] Improper Control of Generation of Code. Phoenix Contact published advisory VDE-2025-074 describing the issue. The vulnerability has an EPSS probability of 0.881%.

Critical Impact
An authenticated low-privileged user can achieve root-level command execution on the device, fully compromising the underlying system.

Affected Products

Phoenix Contact device with Web-based management (see vendor advisory VDE-2025-074)
Specific product models and firmware versions: refer to the Phoenix Contact Security Advisory

Discovery Timeline

2025-10-14 - CVE-2025-41699 published to NVD
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2025-41699

Vulnerability Analysis

The vulnerability resides in the Web-based management interface of the affected device. Configuration parameters submitted through this interface are passed to the underlying system without proper validation or sanitization. An attacker who can authenticate with even minimal privileges can craft configuration values that are later interpreted as code or shell commands by a privileged process. Because the executing process runs as root, the injected commands inherit full system privileges. This collapses the security boundary between the management plane and the underlying operating system.

Root Cause

The root cause is improper control of generation of code [CWE-94]. The management application incorporates attacker-controlled configuration data into a code or command context without enforcing context-appropriate encoding, allow-listing, or argument separation. The privilege separation that normally restricts a low-privileged Web user is bypassed because the configuration is consumed by a root-owned process.

Attack Vector

The attack vector is network-based and requires authentication. The attacker needs an account on the Web-based management interface but no user interaction is required. The attacker logs in, submits a malicious configuration change through a Web request, and triggers the code path that executes the injected payload as root. Refer to the Phoenix Contact Security Advisory for vendor-published technical details.

Detection Methods for CVE-2025-41699

Indicators of Compromise

Unexpected configuration changes submitted by low-privileged Web management accounts
New or unusual processes spawned by the management daemon running as root
Outbound network connections from the device to unfamiliar destinations following a configuration change
Modifications to startup scripts, cron entries, or system files that do not correlate with administrator activity

Detection Strategies

Audit Web-based management authentication logs for low-privileged accounts performing configuration writes
Correlate configuration change events with subsequent shell or interpreter invocations under the management service
Inspect configuration fields for shell metacharacters such as ;, |, `, $(, and newline sequences
Establish a baseline of expected child processes for the management daemon and alert on deviations

Monitoring Recommendations

Forward device syslog and Web management audit logs to a centralized SIEM for retention and correlation
Alert on creation of new Web management accounts and on privilege changes
Monitor network segments hosting operational technology devices for anomalous east-west traffic
Track firmware version inventory to confirm patched builds are deployed across the fleet

How to Mitigate CVE-2025-41699

Immediate Actions Required

Apply the firmware update referenced in Phoenix Contact advisory VDE-2025-074 as soon as it is available
Restrict network access to the Web-based management interface to trusted administrative networks only
Review all Web management accounts and remove unused or shared low-privilege accounts
Enforce strong, unique passwords and rotate credentials for any account that may have been exposed

Patch Information

Consult the Phoenix Contact Security Advisory for the list of affected products, fixed firmware versions, and vendor-recommended remediation steps. Apply the fixed firmware to every affected device in the environment.

Workarounds

Place affected devices behind a firewall or VPN and block external access to the management interface
Limit management access to a dedicated administrative VLAN with strict access control lists
Disable or remove non-essential Web management accounts until the patch is applied
Monitor configuration change events closely and require change-control approval for management writes

bash

# Configuration example: restrict management access at the network edge
# Replace 10.10.10.0/24 with your administrative subnet and <device_ip> with the device address
iptables -A FORWARD -s 10.10.10.0/24 -d <device_ip> -p tcp --dport 443 -j ACCEPT
iptables -A FORWARD -d <device_ip> -p tcp --dport 443 -j DROP
iptables -A FORWARD -d <device_ip> -p tcp --dport 80 -j DROP