CVE-2026-2884: D-Link DWR-M960 Buffer Overflow Flaw

CVE-2026-2884 Overview

A stack-based buffer overflow vulnerability has been identified in the D-Link DWR-M960 wireless router firmware version 1.01.07. The vulnerability exists in the function sub_41914C within the file /boafrm/formWanConfigSetup, which is part of the WAN Interface Setting Handler component. An attacker can manipulate the submit-url argument to trigger a stack-based buffer overflow, potentially leading to remote code execution or denial of service.

Critical Impact

This vulnerability allows remote attackers with low privileges to potentially execute arbitrary code or crash affected D-Link DWR-M960 devices by exploiting the buffer overflow in the WAN configuration handler.

Affected Products

• D-Link DWR-M960 Firmware version 1.01.07
• D-Link DWR-M960 Hardware revision B1

Discovery Timeline

• 2026-02-21 - CVE-2026-2884 published to NVD
• 2026-02-23 - Last updated in NVD database

Technical Details for CVE-2026-2884

Vulnerability Analysis

This vulnerability is classified under CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer). The flaw resides in the WAN Interface Setting Handler, specifically within the sub_41914C function that processes incoming form data at the /boafrm/formWanConfigSetup endpoint. When the submit-url parameter is manipulated with an oversized or malformed input, the application fails to properly validate the input length before copying it to a fixed-size stack buffer, resulting in a classic stack-based buffer overflow condition.

The vulnerability can be exploited remotely over the network without requiring user interaction, though it does require low-level authentication privileges. Successful exploitation could allow an attacker to overwrite critical stack data, including the return address, potentially gaining control of program execution flow.

Root Cause

The root cause stems from inadequate input validation and bounds checking in the sub_41914C function. The firmware does not properly verify the length of the submit-url argument before copying it into a stack-allocated buffer. This absence of boundary validation allows attackers to supply data exceeding the buffer's capacity, corrupting adjacent stack memory and potentially overwriting saved return addresses or other critical control data.

Attack Vector

The attack is network-accessible and targets the web management interface of the D-Link DWR-M960 router. An authenticated attacker can craft a malicious HTTP request to the /boafrm/formWanConfigSetup endpoint with an oversized submit-url parameter. Since the exploit has been publicly disclosed, attackers with knowledge of the vulnerability can construct payloads designed to overflow the stack buffer and hijack execution flow.

The attack requires low-privilege authentication to the router's web interface, but does not require user interaction. Given the nature of embedded device security, many installations may still use default credentials, increasing the exploitability of this vulnerability.

Detection Methods for CVE-2026-2884

Indicators of Compromise

• Unusual HTTP POST requests to /boafrm/formWanConfigSetup with abnormally long submit-url parameter values
• Unexpected router crashes or reboots following web interface access
• Anomalous outbound network connections originating from the router
• Changes to router configuration without administrative authorization

Detection Strategies

• Monitor HTTP traffic to D-Link DWR-M960 devices for POST requests containing oversized parameters in WAN configuration endpoints
• Implement intrusion detection rules to flag requests to /boafrm/formWanConfigSetup with submit-url values exceeding normal length thresholds
• Configure network-based monitoring to detect buffer overflow attack patterns targeting embedded web servers
• Review router access logs for suspicious authentication attempts followed by configuration changes

Monitoring Recommendations

• Enable logging on network firewalls for all traffic to and from D-Link DWR-M960 management interfaces
• Deploy network segmentation to isolate router management interfaces from untrusted networks
• Implement real-time alerting for any detected exploitation attempts targeting vulnerable endpoints
• Regularly audit router configurations for unauthorized modifications

How to Mitigate CVE-2026-2884

Immediate Actions Required

• Restrict access to the router's web management interface to trusted IP addresses only
• Ensure strong, non-default administrative credentials are configured on all D-Link DWR-M960 devices
• Place the router management interface behind a VPN or firewall to limit network exposure
• Monitor for any firmware updates from D-Link that address this vulnerability
• Consider replacing end-of-life devices if vendor patches are not forthcoming

Patch Information

As of the last update on 2026-02-23, no official patch information has been released by D-Link for this vulnerability. Users should monitor the D-Link Support Website for security advisories and firmware updates. Additional technical details can be found in the GitHub Issue Discussion and the VulDB Entry #347178.

Workarounds

• Disable remote management access to the router's web interface if not required
• Implement firewall rules to block external access to the web management port (typically TCP 80/443)
• Use network access control lists (ACLs) to restrict management interface access to specific administrator workstations
• Consider deploying a separate, more secure router for critical network segments until a patch is available

# Example iptables rules to restrict management interface access
# Block external access to router management interface
iptables -A INPUT -p tcp --dport 80 -s 192.168.1.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 80 -j DROP
iptables -A INPUT -p tcp --dport 443 -s 192.168.1.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -j DROP