CVE-2026-2926 Overview
A critical stack-based buffer overflow vulnerability has been identified in D-Link DWR-M960 firmware version 1.01.07. This flaw affects the function sub_4237AC within the file /boafrm/formLteSetup, which is part of the LTE Configuration Endpoint component. By manipulating the submit-url argument, a remote attacker with low privileges can trigger a stack-based buffer overflow condition, potentially leading to arbitrary code execution on the affected device.
Critical Impact
Remote attackers can exploit this vulnerability to execute arbitrary code on vulnerable D-Link DWR-M960 routers, potentially gaining full control of the network device and enabling further attacks on the connected network infrastructure.
Affected Products
- D-Link DWR-M960 Firmware version 1.01.07
- D-Link DWR-M960 Hardware revision B1
- D-Link DWR-M960 LTE Router
Discovery Timeline
- 2026-02-22 - CVE-2026-2926 published to NVD
- 2026-02-23 - Last updated in NVD database
Technical Details for CVE-2026-2926
Vulnerability Analysis
This vulnerability is classified as CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer), which represents a fundamental memory safety issue in the D-Link router firmware. The vulnerable code path exists within the LTE configuration functionality, specifically in the function sub_4237AC that processes form submissions at the /boafrm/formLteSetup endpoint.
The flaw allows attackers to send crafted requests that overflow stack-allocated buffers, corrupting adjacent memory structures including return addresses and saved registers. When exploited, this can redirect program execution to attacker-controlled code, effectively compromising the entire router.
The vulnerability is particularly concerning for IoT network devices because routers often serve as the gateway between internal networks and the internet, making them high-value targets for establishing persistent access or pivoting to other systems.
Root Cause
The root cause lies in insufficient input validation and boundary checking when processing the submit-url parameter in the LTE configuration form handler. The firmware fails to properly validate the length of user-supplied input before copying it into a fixed-size stack buffer. This classic buffer overflow pattern occurs when the application uses unsafe memory copy operations without verifying that the destination buffer can accommodate the source data.
The vulnerable function sub_4237AC does not implement proper bounds checking, allowing an attacker to provide an oversized submit-url value that exceeds the allocated buffer space, thereby overwriting adjacent stack memory.
Attack Vector
The attack can be launched remotely over the network against the device's web management interface. An attacker with low-level privileges (authenticated access) can craft a malicious HTTP request to the /boafrm/formLteSetup endpoint with an oversized submit-url parameter.
The exploitation process involves:
- Accessing the LTE Configuration Endpoint at /boafrm/formLteSetup
- Submitting a crafted request with an oversized submit-url parameter
- The malicious input overflows the stack buffer in sub_4237AC
- Stack control structures are overwritten, potentially redirecting execution flow
- Attacker-controlled code executes with the privileges of the web server process
Technical details regarding the specific exploitation mechanism can be found in the GitHub Issue Discussion where the vulnerability was disclosed.
Detection Methods for CVE-2026-2926
Indicators of Compromise
- Unusual HTTP POST requests to /boafrm/formLteSetup containing abnormally long submit-url parameters
- Unexpected router reboots or service interruptions related to the web management interface
- Modified router configurations or unauthorized administrative access
- Network traffic anomalies originating from the router to unknown external destinations
Detection Strategies
- Implement network intrusion detection rules to identify HTTP requests with oversized parameters targeting D-Link management interfaces
- Monitor web server logs on the device for malformed requests to the LTE configuration endpoint
- Deploy network traffic analysis to detect exploitation attempts against vulnerable endpoints
- Use vulnerability scanning tools to identify devices running firmware version 1.01.07
Monitoring Recommendations
- Enable and centralize logging for all D-Link router management interface access attempts
- Configure alerts for failed authentication attempts followed by successful access to configuration endpoints
- Monitor for unexpected configuration changes on network devices
- Implement network segmentation to restrict access to router management interfaces
How to Mitigate CVE-2026-2926
Immediate Actions Required
- Restrict access to the router's web management interface to trusted IP addresses only
- Place the management interface on a dedicated management VLAN inaccessible from untrusted networks
- Disable remote management access if not required for operations
- Monitor for any suspicious activity targeting the affected device
Patch Information
At the time of publication, no official patch has been released by D-Link for this vulnerability. Organizations should monitor the D-Link Security Portal for firmware updates addressing CVE-2026-2926. Additional technical details and tracking information are available via VulDB Vulnerability #347273.
Workarounds
- Implement firewall rules to block external access to the /boafrm/formLteSetup endpoint
- Restrict management interface access to specific trusted IP addresses using access control lists
- Consider replacing end-of-life devices with actively supported alternatives if patches are not forthcoming
- Deploy network-based intrusion prevention systems to detect and block exploitation attempts
# Example iptables rule to restrict management interface access
# Replace 192.168.1.0/24 with your trusted management network
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
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
