CVE-2026-18589 in WL-NU516U1
Summary
by MITRE • 08/03/2026
A vulnerability was found in Wavlink WL-NU516U1 708c073-mt7628. This impacts the function change_password of the file nas.cgi. The manipulation of the argument User1Passwd results in stack-based buffer overflow. The attack can be executed remotely. The exploit has been made public and could be used. The affected component should be upgraded. The vendor was contacted early, responded in a very professional manner and quickly released a fixed version of the affected product.
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Analysis
by VulDB Data Team • 08/03/2026
This vulnerability resides within the Wavlink WL-NU516U1 708c073-mt7628 wireless USB adapter firmware, specifically targeting the change_password function implemented in the nas.cgi file. The flaw represents a classic stack-based buffer overflow condition that occurs when processing the User1Passwd argument parameter, creating a critical security weakness that allows remote code execution capabilities. The vulnerability's exploitation potential is heightened by its remote accessibility and the public availability of exploit code, making it particularly dangerous for unpatched devices. The affected device operates within the consumer and small office networking space where such vulnerabilities can be leveraged to compromise entire network infrastructures through compromised gateway devices.
The technical implementation of this buffer overflow stems from insufficient input validation and bounds checking within the nas.cgi script's password change functionality. When the User1Passwd parameter exceeds the allocated stack buffer size, it overflows into adjacent memory locations, potentially allowing attackers to overwrite critical program execution data such as return addresses or function pointers. This type of vulnerability maps directly to CWE-121 Stack-based Buffer Overflow, which is classified under the broader category of buffer overflow conditions that can lead to arbitrary code execution and system compromise. The attack surface is particularly concerning as it allows remote exploitation without requiring physical access to the device, enabling attackers to leverage network-based attacks against vulnerable systems.
The operational impact of this vulnerability extends beyond simple password modification functionality, potentially allowing attackers to gain full administrative control over the affected wireless adapter and subsequently compromise connected networks. Network administrators face significant risk as these devices often serve as primary gateway points for home or small office networks, making them attractive targets for persistent attackers seeking long-term access. The vulnerability's public exploit availability means that even non-technical threat actors can leverage this weakness, significantly increasing the attack surface and potential damage. According to ATT&CK framework's T1072 software deployment tools, this represents a critical compromise vector where attackers can deploy malicious payloads through compromised network devices.
The vendor demonstrated exemplary security response behavior by acknowledging the vulnerability promptly and releasing a patched firmware version in a timely manner. This professional handling aligns with industry best practices for vulnerability disclosure and remediation, though it also highlights the importance of regular firmware updates for consumer networking equipment. Organizations should implement immediate mitigation strategies including disabling unnecessary remote management features, updating firmware to the latest versions, and monitoring network traffic for signs of exploitation attempts. The rapid vendor response serves as a positive example of coordinated vulnerability disclosure practices that help minimize exposure time for affected users while maintaining transparency in the security community.