CVE-2025-5492: D-Link DI-500WF-WT Firmware RCE Vulnerability

CVE-2025-5492 Overview

CVE-2025-5492 is a command injection vulnerability affecting D-Link DI-500WF-WT routers running firmware versions up to 20250511. The flaw resides in the sub_456DE8 function within the /usr/sbin/jhttpd component, reachable through the /msp_info.htm?flag=cmd endpoint. Attackers can manipulate the cmd argument to inject arbitrary operating system commands. The vulnerability is exploitable remotely over the network and requires low-level privileges. The issue is classified under [CWE-74] (Improper Neutralization of Special Elements in Output Used by a Downstream Component).

Critical Impact
Authenticated remote attackers can inject commands into the embedded HTTP daemon, potentially executing arbitrary system commands on affected D-Link DI-500WF-WT devices.

Affected Products

D-Link DI-500WF-WT hardware device
D-Link DI-500WF-WT firmware versions up to 20250511
Embedded jhttpd web service component

Discovery Timeline

2025-06-03 - CVE-2025-5492 published to NVD
2025-07-15 - Last updated in NVD database

Technical Details for CVE-2025-5492

Vulnerability Analysis

The vulnerability exists in the sub_456DE8 function exposed through the /msp_info.htm handler of the jhttpd web server binary located at /usr/sbin/jhttpd. When a client sends a request containing the flag=cmd parameter, the handler routes user-controlled data from the cmd argument into a downstream command execution path. The application fails to neutralize shell metacharacters before passing the input to the underlying operating system. This enables attackers to append or chain arbitrary commands to the intended operation. The EPSS score for this vulnerability is 2.886% at the 85th percentile, indicating elevated probability of exploitation activity compared to typical CVEs.

Root Cause

The root cause is improper input neutralization in the sub_456DE8 function. The function consumes the cmd HTTP parameter and forwards the value to a system-level command interpreter without validation or escaping of shell control characters such as ;, |, &, and backticks. This mirrors a long-running pattern of unsafe command construction in embedded HTTP daemons shipped with consumer and small business routers.

Attack Vector

An attacker reaches the vulnerable handler by sending an HTTP request to /msp_info.htm?flag=cmd on the device's management interface. The attacker supplies a crafted value for the cmd parameter containing shell metacharacters followed by an injected command. If the management interface is reachable from the wide area network, exploitation is possible over the internet. If restricted to the LAN, an attacker on the local network or pivoting from a compromised internal host can trigger the flaw. The attack requires low privileges on the management interface but no user interaction.

No verified public proof-of-concept code is available at the time of writing. See the VulDB entry #310909 for additional technical details.

Detection Methods for CVE-2025-5492

Indicators of Compromise

HTTP requests to /msp_info.htm containing the flag=cmd parameter with shell metacharacters such as ;, |, &, $(, or backticks in the cmd value
Unexpected child processes spawned by the jhttpd binary at /usr/sbin/jhttpd
Outbound connections from the router to unknown hosts following inbound requests to the management interface
New or modified files in writable filesystem locations on the device after suspicious HTTP traffic

Detection Strategies

Inspect web server and reverse proxy logs for requests to /msp_info.htm?flag=cmd originating from non-administrative sources
Apply network intrusion detection signatures that match shell metacharacters in the cmd query parameter of HTTP traffic destined for D-Link management interfaces
Baseline normal management traffic to the router and alert on deviations in request frequency, source IP, or User-Agent strings

Monitoring Recommendations

Forward router syslog and HTTP access logs to a centralized SIEM for retention and correlation
Monitor for unauthenticated or low-privilege HTTP sessions issuing requests to administrative endpoints
Track DNS queries and egress flows from the router subnet to identify post-exploitation command-and-control activity

How to Mitigate CVE-2025-5492

Immediate Actions Required

Restrict access to the router's management interface to trusted administrative networks using firewall rules or access control lists
Disable remote (WAN-side) management on the DI-500WF-WT until a vendor patch is verified and applied
Rotate administrative credentials for the device and audit accounts with access to the management interface
Review HTTP access logs for prior requests to /msp_info.htm?flag=cmd and investigate any matches

Patch Information

No vendor security advisory or firmware patch from D-Link is referenced in the available CVE data at the time of publication. Consult the D-Link Official Site and the VulDB CTI entry #310909 for updates on remediation availability.

Workarounds

Place the DI-500WF-WT behind a network segment that blocks inbound HTTP and HTTPS access to the management interface from untrusted zones
Replace the device with a supported model if D-Link does not release a firmware update for this product line
Deploy upstream web application filtering to drop requests containing shell metacharacters in the cmd parameter of /msp_info.htm

bash

# Example iptables rule restricting management interface access to a trusted admin subnet
iptables -A INPUT -p tcp --dport 80 -s 192.0.2.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 80 -j DROP
iptables -A INPUT -p tcp --dport 443 -s 192.0.2.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -j DROP