CVE-2025-3540 Overview
CVE-2025-3540 is a command injection vulnerability affecting H3C Magic NX15, Magic NX30 Pro, Magic NX400, and Magic R3010 routers running firmware up to V100R014. The flaw resides in the FCGI_WizardProtoProcess function handling requests to /api/wizard/getCapability within the HTTP POST Request Handler component. An authenticated attacker on the adjacent network can manipulate request parameters to inject and execute arbitrary operating system commands. The vulnerability is classified under CWE-74 for improper neutralization of special elements. A public proof-of-concept has been released, increasing the likelihood of active exploitation attempts.
Critical Impact
Successful exploitation grants attackers arbitrary command execution on affected H3C Magic routers, enabling full device compromise, traffic interception, and lateral movement within the local network.
Affected Products
- H3C Magic NX15 (firmware up to V100R014)
- H3C Magic NX30 Pro and Magic NX400 (firmware up to V100R014)
- H3C Magic R3010 (firmware up to V100R014)
Discovery Timeline
- 2025-04-13 - CVE-2025-3540 published to NVD
- 2026-06-17 - Last updated in NVD database
Technical Details for CVE-2025-3540
Vulnerability Analysis
The vulnerability resides in the FCGI_WizardProtoProcess function, which processes HTTP POST requests directed at the /api/wizard/getCapability endpoint. This endpoint is part of the router's setup wizard interface and accepts user-supplied parameters that are passed to underlying system commands without proper sanitization. Attackers craft malicious POST payloads containing shell metacharacters, which the FastCGI handler forwards to a command interpreter on the device. Execution occurs in the context of the web management process, which on most embedded routers runs with elevated or root privileges.
Root Cause
The defect is an [CWE-74] input neutralization failure. The FCGI_WizardProtoProcess function concatenates attacker-controlled input into a command string executed by the system shell, without escaping shell metacharacters such as ;, |, &, or backticks. This pattern is common in embedded device firmware where developers rely on system() or popen() calls to invoke shell utilities from web handlers.
Attack Vector
Exploitation requires network adjacency, meaning the attacker must reside on the same local network segment as the target router. Low-level authentication credentials are required, though many H3C consumer devices ship with default or weak credentials. The attacker sends a crafted HTTP POST request to /api/wizard/getCapability with injected shell commands embedded in parameter values. Because the attack is restricted to the local network, initial access typically requires compromised Wi-Fi credentials, a rogue guest network device, or another foothold inside the LAN.
A public proof-of-concept is available in the GitHub Gist PoC Repository, which demonstrates the exact request structure and injection payloads. Additional technical detail is catalogued in the VulDB #304579 entry.
Detection Methods for CVE-2025-3540
Indicators of Compromise
- HTTP POST requests to /api/wizard/getCapability containing shell metacharacters (;, |, &, $(), backticks) in body parameters.
- Unexpected outbound connections from the router's management interface to attacker-controlled hosts.
- New or modified processes on the router such as telnetd, nc, or wget invocations spawned by the web management daemon.
- Configuration changes to DNS, firewall rules, or port forwarding that were not initiated by an administrator.
Detection Strategies
- Monitor router web server access logs for POST requests to /api/wizard/* endpoints containing suspicious characters or unusually long parameter values.
- Deploy network intrusion detection signatures that inspect HTTP POST bodies destined for the router management interface on TCP ports 80 and 443.
- Baseline expected administrative traffic on the LAN and alert on requests originating from non-administrator hosts.
Monitoring Recommendations
- Forward router syslog and web access logs to a centralized SIEM for correlation with endpoint telemetry.
- Alert on new listening ports appearing on the router after receiving traffic to the setup wizard endpoints.
- Track DNS query patterns from LAN clients for signs of downstream compromise following router takeover.
How to Mitigate CVE-2025-3540
Immediate Actions Required
- Restrict access to the router web management interface to a dedicated management VLAN or specific administrator IP addresses.
- Change default administrative credentials and enforce strong passwords on all affected H3C Magic routers.
- Disable remote management and WAN-side access to the setup wizard endpoints if enabled.
- Segment untrusted devices (guest Wi-Fi, IoT) from the router management network to reduce adjacent-network exposure.
Patch Information
H3C recommends upgrading the affected firmware. Updates should be obtained from the H3C Software Download Resource and the vendor advisory at H3C Theme Details #229784. Verify the firmware version after upgrade to confirm it is beyond V100R014.
Workarounds
- Block LAN access to /api/wizard/getCapability via an upstream firewall or gateway ACL where feasible.
- Isolate vulnerable routers behind a hardened firewall until firmware updates are applied.
- Monitor and log all HTTP POST traffic to the router management interface and investigate anomalous shell metacharacters.
# Example ACL to restrict router management access to a single admin host
iptables -A FORWARD -d <router-ip> -p tcp --dport 80 -s <admin-ip> -j ACCEPT
iptables -A FORWARD -d <router-ip> -p tcp --dport 80 -j DROP
iptables -A FORWARD -d <router-ip> -p tcp --dport 443 -s <admin-ip> -j ACCEPT
iptables -A FORWARD -d <router-ip> -p tcp --dport 443 -j DROP
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
