CVE-2026-2857 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_423E00 within the /boafrm/formPortFw component, which handles Port Forwarding Configuration. By manipulating the submit-url argument, an authenticated attacker can trigger a buffer overflow condition that may lead to remote code execution or denial of service. The exploit has been publicly disclosed and may be utilized by malicious actors.
Critical Impact
Remote attackers with low-level authentication can exploit this stack-based buffer overflow to potentially execute arbitrary code on affected D-Link DWR-M960 routers, compromising network infrastructure and enabling lateral movement within target environments.
Affected Products
- D-Link DWR-M960 Firmware version 1.01.07
- D-Link DWR-M960 Hardware revision B1
- dlink dwr-m960_firmware
Discovery Timeline
- February 20, 2026 - CVE-2026-2857 published to NVD
- February 23, 2026 - Last updated in NVD database
Technical Details for CVE-2026-2857
Vulnerability Analysis
This vulnerability affects the Port Forwarding Configuration Endpoint in D-Link DWR-M960 routers. The affected function sub_423E00 located in /boafrm/formPortFw fails to properly validate the length of user-supplied input passed through the submit-url parameter. When an attacker supplies an overly long string to this parameter, the application copies this data to a stack buffer without adequate bounds checking, resulting in a classic stack-based buffer overflow condition.
The network-accessible nature of this vulnerability significantly increases its risk profile, as attackers can exploit it remotely without requiring physical access to the device. The vulnerability requires low-privilege authentication, meaning an attacker needs valid credentials but not administrative access to trigger the overflow.
Root Cause
The root cause of CVE-2026-2857 is improper memory bounds validation in the sub_423E00 function (CWE-119: Improper Restriction of Operations within the Bounds of a Memory Buffer). The function does not enforce proper length restrictions when processing the submit-url argument, allowing attackers to write beyond the allocated stack buffer boundaries. This type of vulnerability commonly occurs when string copy or manipulation functions are used without explicit length checks.
Attack Vector
The attack vector for this vulnerability is network-based, targeting the /boafrm/formPortFw endpoint on vulnerable D-Link DWR-M960 devices. An attacker must first obtain valid credentials (low-privilege authentication is sufficient) and then craft a malicious HTTP request with an oversized submit-url parameter value. The overflow occurs when the device processes this request, potentially overwriting the return address on the stack and allowing the attacker to redirect execution to arbitrary code.
The attack methodology involves sending a crafted POST request to the Port Forwarding Configuration endpoint with a specially constructed payload in the submit-url field. Due to the nature of embedded systems, successful exploitation could grant the attacker complete control over the router, enabling network traffic interception, DNS hijacking, or using the device as a pivot point for further attacks.
Additional technical details and proof-of-concept information can be found in the GitHub Issue Discussion and VulDB #347096.
Detection Methods for CVE-2026-2857
Indicators of Compromise
- Unusual HTTP POST requests to /boafrm/formPortFw with abnormally long submit-url parameter values
- Unexpected router reboots or crashes that may indicate exploitation attempts
- Anomalous network traffic patterns originating from or routing through the D-Link DWR-M960 device
- Unauthorized configuration changes to port forwarding rules
Detection Strategies
- Implement network intrusion detection rules to identify HTTP requests containing oversized parameters targeting D-Link router endpoints
- Monitor for repeated authentication attempts followed by requests to /boafrm/formPortFw from external IP addresses
- Deploy web application firewall rules to block requests with submit-url parameters exceeding expected lengths
- Review router access logs for suspicious activity patterns targeting configuration endpoints
Monitoring Recommendations
- Enable and centralize logging for all D-Link router administrative interfaces
- Configure alerts for any external access attempts to router management interfaces
- Implement network segmentation to isolate IoT and network infrastructure devices from general network traffic
- Regularly audit router configurations for unauthorized modifications
How to Mitigate CVE-2026-2857
Immediate Actions Required
- Restrict access to the router's web management interface to trusted internal IP addresses only
- Disable remote management features if not required for operations
- Implement strong authentication credentials and change default passwords
- Place the D-Link DWR-M960 behind a properly configured firewall with strict ingress rules
- Monitor for firmware updates from D-Link and apply them immediately when available
Patch Information
At the time of publication, no official patch information has been released by D-Link for this vulnerability. Network administrators should monitor the D-Link Security Information page for security advisories and firmware updates. Given that the exploit has been publicly disclosed, applying vendor patches as soon as they become available is critical.
For tracking purposes, additional details are available at VulDB CTI ID #347096 and VulDB Submission #754476.
Workarounds
- Restrict management interface access to localhost or specific trusted IP addresses using ACLs
- Disable the web-based management interface entirely if alternative management methods are available
- Implement a VPN requirement for any remote administrative access to the router
- Consider replacing end-of-life or unsupported devices with actively maintained alternatives
# Configuration example: Restrict management access via iptables on upstream firewall
# Block external access to D-Link router management port
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 only from trusted admin workstation
iptables -I FORWARD -s <ADMIN_IP> -d <ROUTER_IP> -p tcp --dport 80 -j ACCEPT
iptables -I FORWARD -s <ADMIN_IP> -d <ROUTER_IP> -p tcp --dport 443 -j ACCEPT
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
