CVE-2026-2854: D-Link DWR-M960 Buffer Overflow Flaw

CVE-2026-2854 Overview

A stack-based buffer overflow vulnerability has been identified in the D-Link DWR-M960 router firmware version 1.01.07. This vulnerability affects the function sub_4611CC within the file /boafrm/formNtp of the NTP Configuration Endpoint. An attacker can exploit this flaw by manipulating the submit-url argument, leading to memory corruption that could allow for unauthorized code execution or system compromise.

The vulnerability is remotely exploitable over the network, making it particularly dangerous for organizations and consumers using the affected D-Link router hardware. An exploit for this vulnerability has been published and may be actively used in attacks.

Critical Impact

Remote attackers can exploit this stack-based buffer overflow to potentially execute arbitrary code on vulnerable D-Link DWR-M960 routers, leading to full device compromise and network infiltration.

Affected Products

• D-Link DWR-M960 Firmware version 1.01.07
• D-Link DWR-M960 Hardware revision B1
• D-Link DWR-M960 4G LTE Router

Discovery Timeline

• February 20, 2026 - CVE-2026-2854 published to NVD
• February 23, 2026 - Last updated in NVD database

Technical Details for CVE-2026-2854

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 NTP configuration endpoint (/boafrm/formNtp) of the D-Link DWR-M960 router's web management interface. When processing the submit-url parameter, the vulnerable function sub_4611CC fails to properly validate the length of user-supplied input before copying it to a fixed-size stack buffer.

The network-accessible nature of this vulnerability means attackers can target vulnerable devices remotely without requiring physical access. Low-privileged authentication is required to reach the vulnerable endpoint, but once accessed, the exploitation complexity is minimal. Successful exploitation can result in complete compromise of confidentiality, integrity, and availability of the affected device.

Root Cause

The root cause of this vulnerability is insufficient bounds checking in the sub_4611CC function when handling the submit-url parameter. The firmware code allocates a fixed-size buffer on the stack and copies user-provided data without verifying that the input length does not exceed the buffer capacity. This classic buffer overflow condition allows attackers to overwrite adjacent stack memory, including return addresses and saved registers.

Attack Vector

The attack is executed remotely over the network by sending a specially crafted HTTP request to the /boafrm/formNtp endpoint. The attacker manipulates the submit-url parameter with an oversized payload designed to overflow the stack buffer. By carefully crafting the overflow data, an attacker can potentially:

1. Overwrite the return address to redirect execution flow
2. Inject shellcode or ROP chains for code execution
3. Crash the device causing denial of service
4. Gain persistent access to the router's underlying operating system

The vulnerability requires low-privilege authentication to access the NTP configuration endpoint, but this is commonly achieved through default credentials or other authentication weaknesses common in IoT devices.

Detection Methods for CVE-2026-2854

Indicators of Compromise

• Unusual HTTP POST requests to /boafrm/formNtp with abnormally large submit-url parameter values
• Router crashes or unexpected reboots following web interface access
• Suspicious outbound network connections from the router to unknown external IP addresses
• Modified router configuration or unexpected firmware changes

Detection Strategies

• Deploy network intrusion detection rules to monitor for oversized HTTP parameters targeting D-Link router endpoints
• Implement web application firewall rules to block requests with excessively long URL parameters to /boafrm/formNtp
• Monitor router syslog output for segmentation faults or memory-related errors
• Conduct regular firmware integrity checks on D-Link DWR-M960 devices

Monitoring Recommendations

• Enable comprehensive logging on network perimeter devices to capture traffic to and from D-Link routers
• Configure SIEM alerts for anomalous HTTP traffic patterns targeting router management interfaces
• Establish baseline network behavior for IoT devices and alert on deviations
• Implement network segmentation to isolate vulnerable router management interfaces from untrusted networks

How to Mitigate CVE-2026-2854

Immediate Actions Required

• Restrict network access to the router's web management interface using firewall rules or access control lists
• Disable remote management features if not required for operations
• Change default administrative credentials to strong, unique passwords
• Monitor the D-Link Security Updates page for firmware patches addressing this vulnerability
• Consider network segmentation to limit exposure of vulnerable devices

Patch Information

At the time of publication, no official patch has been confirmed from D-Link. Organizations should monitor the D-Link website for security advisories and firmware updates addressing CVE-2026-2854. Additional technical details and vulnerability tracking information are available through the VulDB entry #347093 and the GitHub Issue Discussion.

Workarounds

• Disable the web management interface entirely and use console access for router administration
• Implement strict network access controls limiting management interface access to trusted IP addresses only
• Deploy an upstream firewall or IPS with rules blocking oversized HTTP parameters to D-Link endpoints
• Consider replacing affected devices with alternative hardware if patching is not available in a timely manner

# Example: Restrict management interface access via iptables on upstream firewall
# Block external access to the router management interface
iptables -A FORWARD -d <ROUTER_IP> -p tcp --dport 80 -j DROP
iptables -A FORWARD -d <ROUTER_IP> -p tcp --dport 443 -j DROP

# Allow management access only from trusted admin subnet
iptables -I FORWARD -s 192.168.1.0/24 -d <ROUTER_IP> -p tcp --dport 80 -j ACCEPT