CVE-2025-4756: D-Link DI-7003GV2 Firmware DoS Vulnerability

CVE-2025-4756 Overview

A denial of service vulnerability has been identified in the D-Link DI-7003GV2 router firmware version 24.04.18D1 R(68125). The vulnerability exists in the /H5/restart.asp file and can be exploited remotely without authentication. When exploited, an attacker can manipulate requests to this endpoint to cause a denial of service condition, potentially disrupting network connectivity for all devices relying on the affected router.

Critical Impact

Remote attackers can exploit this vulnerability to cause denial of service on affected D-Link routers, disrupting network availability for connected devices without requiring authentication.

Affected Products

• D-Link DI-7003GV2 Firmware version 24.04.18D1 R(68125)
• D-Link DI-7003G Hardware version V2.D1

Discovery Timeline

• May 16, 2025 - CVE-2025-4756 published to NVD
• May 21, 2025 - Last updated in NVD database

Technical Details for CVE-2025-4756

Vulnerability Analysis

This vulnerability is classified under CWE-404 (Improper Resource Shutdown or Release), which indicates the affected code fails to properly release or shut down resources. The vulnerability resides in the web management interface of the D-Link DI-7003GV2 router, specifically within the /H5/restart.asp endpoint. This endpoint appears to handle device restart functionality but lacks proper input validation and resource management.

The network-accessible nature of this vulnerability means attackers can exploit it remotely without requiring any prior authentication or user interaction. The impact is limited to availability, as the vulnerability allows attackers to cause denial of service conditions but does not enable data theft or system compromise.

Root Cause

The root cause stems from improper resource shutdown or release (CWE-404) in the router's web interface. The /H5/restart.asp file does not properly validate or handle incoming requests, allowing malicious manipulation that leads to resource exhaustion or improper state handling. This results in the router becoming unresponsive or forcibly restarting, causing network disruption.

Attack Vector

The attack can be executed remotely over the network by sending crafted HTTP requests to the vulnerable endpoint. The attack requires no authentication, no user interaction, and has low complexity. An attacker with network access to the router's management interface can target the /H5/restart.asp endpoint to trigger the denial of service condition.

The vulnerability mechanism involves sending manipulated requests to the restart endpoint. When the router processes these malformed requests, it fails to properly handle resource allocation, leading to service disruption. Technical details and a proof-of-concept demonstrating the exploitation method have been publicly disclosed on GitHub.

Detection Methods for CVE-2025-4756

Indicators of Compromise

• Unexpected router reboots or service interruptions without administrative action
• Unusual HTTP traffic patterns targeting /H5/restart.asp on the router's management interface
• Network outages coinciding with suspicious access attempts to the router's web interface
• Log entries showing repeated requests to the restart endpoint from external IP addresses

Detection Strategies

• Monitor web server logs on the D-Link router for anomalous requests to /H5/restart.asp
• Implement network traffic analysis to detect repeated requests to router management endpoints
• Configure alerts for unexpected device reboots or availability issues
• Deploy intrusion detection system (IDS) rules to identify exploitation attempts targeting this specific endpoint

Monitoring Recommendations

• Enable logging on the D-Link router if available and regularly review logs for suspicious activity
• Use network monitoring tools to track traffic to router management interfaces
• Implement baseline monitoring for router availability and alert on deviations
• Consider deploying a web application firewall (WAF) in front of router management interfaces if architecture permits

How to Mitigate CVE-2025-4756

Immediate Actions Required

• Restrict network access to the router's web management interface to trusted internal networks only
• Disable remote management access if not required for business operations
• Implement firewall rules to block external access to the router's HTTP/HTTPS management ports
• Monitor for firmware updates from D-Link addressing this vulnerability

Patch Information

At the time of publication, no vendor patch has been confirmed for this vulnerability. Organizations should monitor the D-Link Official Website for security advisories and firmware updates. Additional technical details about this vulnerability can be found at VulDB.

Workarounds

• Configure network ACLs to limit access to the management interface to specific trusted IP addresses
• Place the router's management interface on a separate VLAN inaccessible from untrusted networks
• If the device supports it, disable the web management interface entirely and use alternative management methods
• Consider replacing the device with a supported model if D-Link does not release a security patch

# Example firewall rule to restrict management interface access (adjust for your environment)
# Block external access to router management port (typically 80/443)
iptables -A INPUT -p tcp --dport 80 -s ! 192.168.1.0/24 -j DROP
iptables -A INPUT -p tcp --dport 443 -s ! 192.168.1.0/24 -j DROP