CVE-2026-2853: D-Link DWR-M960 Buffer Overflow Flaw

CVE-2026-2853 Overview

A stack-based buffer overflow vulnerability has been identified in the D-Link DWR-M960 mobile router firmware version 1.01.07. This vulnerability affects the function sub_462E14 within the System Log Configuration Endpoint located at /boafrm/formSysLog. By manipulating the submit-url argument, an attacker can trigger a stack-based buffer overflow condition, potentially leading to arbitrary code execution or denial of service on the affected device.

Critical Impact

This network-accessible vulnerability in D-Link DWR-M960 routers allows authenticated remote attackers to exploit a stack-based buffer overflow, potentially achieving arbitrary code execution or causing device instability. The exploit is publicly available, increasing the risk of active exploitation.

Affected Products

• D-Link DWR-M960 Firmware version 1.01.07
• D-Link DWR-M960 Hardware revision B1
• D-Link DWR-M960 mobile router devices running vulnerable firmware

Discovery Timeline

• 2026-02-20 - CVE-2026-2853 published to NVD
• 2026-02-23 - Last updated in NVD database

Technical Details for CVE-2026-2853

Vulnerability Analysis

This vulnerability is a classic stack-based buffer overflow (CWE-119) in embedded network device firmware. The vulnerable function sub_462E14 fails to properly validate the length of user-supplied input passed via the submit-url parameter before copying it to a fixed-size stack buffer. When an attacker provides an oversized input value, the data overwrites adjacent memory on the stack, including potentially critical control flow data such as the return address.

The vulnerability is accessible remotely over the network, requiring low-privilege authentication to reach the affected endpoint. No user interaction is required for exploitation, and the attack complexity is considered low due to the straightforward nature of the buffer overflow condition.

Root Cause

The root cause of this vulnerability is improper bounds checking in the sub_462E14 function when processing the submit-url argument. The function copies user-controlled input into a stack-allocated buffer without verifying that the input length does not exceed the buffer's capacity. This is a common vulnerability pattern in embedded device firmware where memory constraints often lead developers to use fixed-size buffers without implementing proper input validation.

Attack Vector

The attack can be executed remotely by sending a crafted HTTP request to the /boafrm/formSysLog endpoint on the target device. The attacker must have low-level authenticated access to the router's web management interface. By providing a maliciously crafted submit-url parameter containing an oversized payload, the attacker can overflow the stack buffer.

The exploitation flow involves:

1. Authenticating to the router's web interface with valid credentials
2. Sending a malformed request to the System Log Configuration endpoint
3. Including an oversized submit-url parameter value designed to overflow the stack buffer
4. Overwriting the return address or other critical stack data to hijack program execution

The vulnerability mechanism involves improper memory buffer bounds handling in the sub_462E14 function. When the submit-url parameter exceeds the expected buffer size, the overflow corrupts adjacent stack memory. Technical exploitation details are available in the GitHub Issue Tracker and the VulDB advisory.

Detection Methods for CVE-2026-2853

Indicators of Compromise

• Unexpected router reboots or crashes when accessing the System Log Configuration page
• Anomalous HTTP POST requests to /boafrm/formSysLog with unusually large submit-url parameter values
• Evidence of exploitation attempts in router access logs showing malformed requests to the vulnerable endpoint

Detection Strategies

• Monitor network traffic for HTTP requests to /boafrm/formSysLog containing oversized parameter values
• Implement intrusion detection signatures to identify buffer overflow patterns targeting this endpoint
• Deploy web application firewall rules to block requests with excessively long submit-url parameters
• Review router logs for authentication anomalies followed by System Log Configuration access

Monitoring Recommendations

• Enable verbose logging on D-Link DWR-M960 devices if supported by firmware
• Monitor for unusual outbound connections from the router that may indicate post-exploitation activity
• Track firmware versions across your network to identify vulnerable D-Link devices
• Configure alerts for repeated failed or anomalous requests to router management interfaces

How to Mitigate CVE-2026-2853

Immediate Actions Required

• Restrict administrative access to the D-Link DWR-M960 web interface to trusted networks only
• Implement strong authentication credentials and change default passwords immediately
• Consider disabling remote management functionality if not required
• Place affected devices behind a firewall that filters access to the management interface
• Monitor the D-Link Security page for firmware updates addressing this vulnerability

Patch Information

At the time of publication, no official patch has been released by D-Link for this vulnerability. Organizations should monitor D-Link's official security advisories for updates. The vulnerability affects firmware version 1.01.07, and users should upgrade to a patched version when one becomes available.

For additional technical details, refer to the VulDB advisory and the GitHub issue tracker.

Workarounds

• Disable remote management access to the router's web interface entirely
• Implement network segmentation to isolate vulnerable devices from untrusted networks
• Use access control lists (ACLs) to restrict which IP addresses can access the management interface
• Consider replacing end-of-life devices that may not receive security updates

# Network access restriction example (on upstream firewall)
# 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