CVE-2026-2958: D-Link DWR-M960 Buffer Overflow Vulnerability

CVE-2026-2958 Overview

A stack-based buffer overflow vulnerability has been identified in the D-Link DWR-M960 mobile router running firmware version 1.01.07. The vulnerability exists in the sub_457C5C function within the /boafrm/formWsc file, where improper handling of the save_apply argument allows an attacker to overflow the stack buffer. This firmware vulnerability can be exploited remotely over the network, potentially enabling attackers to execute arbitrary code or cause denial of service on affected devices. The exploit for this vulnerability has been publicly disclosed, increasing the risk of active exploitation in the wild.

Critical Impact

Remote attackers can exploit this stack-based buffer overflow to potentially achieve code execution on vulnerable D-Link DWR-M960 routers, compromising network security and enabling further attacks on connected devices.

Affected Products

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

Discovery Timeline

• 2026-02-23 - CVE-2026-2958 published to NVD
• 2026-02-23 - Last updated in NVD database

Technical Details for CVE-2026-2958

Vulnerability Analysis

This vulnerability is classified as CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer), manifesting as a stack-based buffer overflow in the D-Link DWR-M960 router's web management interface. The vulnerable function sub_457C5C processes user-supplied input from the save_apply parameter without proper bounds checking, allowing attackers to write beyond the allocated stack buffer.

The attack can be initiated remotely with low attack complexity, requiring only low-level privileges to execute. No user interaction is necessary for exploitation, making this vulnerability particularly dangerous for internet-facing devices. Successful exploitation could result in complete compromise of confidentiality, integrity, and availability of the affected router.

Root Cause

The root cause of this vulnerability lies in insufficient input validation within the sub_457C5C function. When processing the save_apply argument in the /boafrm/formWsc endpoint, the firmware fails to properly validate the length of user-supplied data before copying it to a fixed-size stack buffer. This classic buffer overflow pattern allows attackers to overwrite adjacent stack memory, including return addresses and other critical data structures.

Attack Vector

The vulnerability is exploitable via network access to the router's web management interface. An attacker can craft a malicious HTTP request to the /boafrm/formWsc endpoint with an oversized save_apply parameter value. When the vulnerable function processes this input, the stack buffer is overflowed, potentially allowing the attacker to:

1. Overwrite the function's return address to redirect execution flow
2. Inject and execute shellcode within the router's memory space
3. Cause denial of service by corrupting critical stack data
4. Gain persistent access to the router for further network compromise

The vulnerability is exploitable remotely without requiring physical access to the device, and the exploit has been publicly disclosed, which increases the likelihood of exploitation attempts.

Detection Methods for CVE-2026-2958

Indicators of Compromise

• Unusual HTTP requests to /boafrm/formWsc with abnormally large save_apply parameter values
• Router crashes or unexpected reboots following web interface access attempts
• Unexplained changes to router configuration or firmware settings
• Network traffic anomalies originating from the router to unknown external destinations

Detection Strategies

• Monitor HTTP traffic to D-Link router management interfaces for oversized POST parameters
• Implement intrusion detection rules to alert on requests to /boafrm/formWsc containing unusually long parameter values
• Deploy network segmentation to isolate IoT devices and enable focused monitoring
• Configure logging on network firewalls to capture all traffic to router management ports

Monitoring Recommendations

• Enable verbose logging on network perimeter devices monitoring traffic to D-Link routers
• Set up alerts for repeated failed authentication attempts or anomalous request patterns to router interfaces
• Regularly review router system logs for signs of exploitation or unauthorized access
• Consider implementing a network monitoring solution that can detect buffer overflow attack signatures

How to Mitigate CVE-2026-2958

Immediate Actions Required

• Restrict access to the router's web management interface to trusted internal networks only
• Disable remote management features if not required for operations
• Implement firewall rules to block external access to ports 80 and 443 on the router
• Monitor for firmware updates from D-Link and apply patches as soon as they become available
• Consider replacing affected devices with models that receive regular security updates

Patch Information

At the time of publication, no official patch has been released by D-Link for this vulnerability. Administrators should monitor the D-Link Security Resource page for security advisories and firmware updates. Additional technical details can be found in the GitHub Issue Discussion and the VulDB advisory.

Workarounds

• Implement network access control lists (ACLs) to restrict management interface access to specific trusted IP addresses
• Place the router behind a separate firewall that can filter malicious requests before they reach the device
• Disable the web-based management interface entirely if command-line management is available and sufficient
• Segment the network to isolate potentially vulnerable devices from critical infrastructure

# Example firewall rule to restrict router management access (iptables)
# Block external access to router management ports
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

# Allow management only from specific admin workstation
iptables -A INPUT -p tcp --dport 80 -s 192.168.1.100 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -s 192.168.1.100 -j ACCEPT