CVE-2025-50668: D-Link DI-8003 Buffer Overflow Vulnerability

CVE-2025-50668 Overview

CVE-2025-50668 is a buffer overflow vulnerability [CWE-120] in the D-Link DI-8003 router running firmware version 16.07.26A1. The flaw resides in the /web_list_opt.asp endpoint, where the s parameter is processed without proper bounds checking. Remote attackers can send a crafted HTTP request with an oversized s parameter to trigger memory corruption. Successful exploitation results in a denial-of-service condition on the affected device. The vulnerability requires no authentication and no user interaction, making it reachable across the network.

Critical Impact

Unauthenticated remote attackers can crash the D-Link DI-8003 router by sending a malformed HTTP request to /web_list_opt.asp, disrupting network connectivity for downstream users.

Affected Products

• D-Link DI-8003 router (hardware)
• D-Link DI-8003 firmware version 16.07.26A1
• Deployments exposing the web management interface to untrusted networks

Discovery Timeline

• 2026-04-08 - CVE-2025-50668 published to NVD
• 2026-04-10 - Last updated in NVD database

Technical Details for CVE-2025-50668

Vulnerability Analysis

The vulnerability stems from improper handling of user-supplied data in the DI-8003 web management interface. The /web_list_opt.asp endpoint accepts an s parameter from HTTP requests and copies its value into a fixed-size stack or heap buffer. The handler does not validate the length of the input before the copy operation. Supplying an s value larger than the destination buffer overwrites adjacent memory regions.

Because the web service runs as a privileged process on the embedded device, memory corruption disrupts the HTTP daemon and supporting network services. The CWE-120 classification confirms the root issue as a classic buffer copy without checking input size. Exploitation produces an availability impact, consistent with a crash of the management plane and dependent routing functions.

Root Cause

The root cause is missing input length validation in the request handler for /web_list_opt.asp. The firmware copies the s parameter using an unbounded string operation, treating attacker-controlled input as trusted. No canary, ASLR, or stack protection mechanism on the embedded platform reliably prevents the overflow.

Attack Vector

An attacker reaches the vulnerability over the network by issuing a single HTTP request to the device's web interface. No credentials or user interaction are required. The attacker submits an oversized value in the s parameter, triggering the overflow during request parsing. The result is a process crash and loss of router availability until the device is restarted.

No verified proof-of-concept code or exploit is publicly available at this time. Refer to the GitHub IoT Vulnerability Collection for technical context.

Detection Methods for CVE-2025-50668

Indicators of Compromise

• Unexpected reboots or crashes of the DI-8003 router with no operator action.
• HTTP requests to /web_list_opt.asp containing unusually long s parameter values.
• Loss of routing or DHCP services followed by automatic device recovery.
• Repeated connection attempts to the device's web management port from external addresses.

Detection Strategies

• Inspect web server and syslog output for malformed requests targeting /web_list_opt.asp.
• Deploy network intrusion detection signatures that flag HTTP requests with oversized query string parameters destined for D-Link management interfaces.
• Correlate router availability events with inbound HTTP traffic to the device's management port.

Monitoring Recommendations

• Forward router syslog and SNMP traps to a centralized logging platform for anomaly review.
• Alert on HTTP request bodies or query strings exceeding length thresholds against embedded device interfaces.
• Track uptime and crash counters on the DI-8003 to identify exploitation attempts producing denial of service.

How to Mitigate CVE-2025-50668

Immediate Actions Required

• Restrict access to the DI-8003 web management interface to trusted management VLANs or specific administrator IP addresses.
• Disable remote (WAN-side) management on the device until a vendor patch is applied.
• Monitor the D-Link Security Bulletin page for firmware updates addressing CVE-2025-50668.
• Inventory all DI-8003 deployments and confirm firmware version 16.07.26A1 exposure.

Patch Information

D-Link has not published a fixed firmware version referenced in the NVD entry at the time of writing. Review the D-Link Security Bulletin for the latest advisories and apply firmware updates as soon as they become available. Subscribe to vendor notifications to track remediation for this device family.

Workarounds

• Block inbound TCP traffic to the device's HTTP/HTTPS management ports at the perimeter firewall.
• Place the router's management interface on an isolated administrative network segment.
• Apply ACLs that permit web management connections only from authorized administrator workstations.
• Consider replacing end-of-support D-Link models if no firmware update is released for this vulnerability.

# Example iptables rule restricting access to the DI-8003 management interface
iptables -A FORWARD -p tcp -d <DI-8003-IP> --dport 80 -s <admin-subnet> -j ACCEPT
iptables -A FORWARD -p tcp -d <DI-8003-IP> --dport 80 -j DROP
iptables -A FORWARD -p tcp -d <DI-8003-IP> --dport 443 -s <admin-subnet> -j ACCEPT
iptables -A FORWARD -p tcp -d <DI-8003-IP> --dport 443 -j DROP