CVE-2026-3613 identifies a critical stack-based buffer overflow vulnerability in the Wavlink WL-NU516U1 wireless adapter firmware version V240425. The vulnerability resides in the CGI login interface (/cgi-bin/login.cgi), specifically within the sub_401A0C function, which processes the 'ipaddr' parameter. Improper input validation or bounds checking on this argument allows an attacker to overwrite the stack memory, leading to a buffer overflow condition. This flaw can be triggered remotely over the network without requiring authentication or user interaction, making it highly exploitable. The overflow can be leveraged to execute arbitrary code with the privileges of the affected service, potentially compromising device integrity and confidentiality. The CVSS v4.0 score is 8.6 (high), reflecting the network attack vector, low attack complexity, no privileges or user interaction required, and high impact on confidentiality, integrity, and availability. While no active exploitation has been reported, a public exploit exists, increasing the urgency for remediation. The vendor was contacted early, but no official patch or mitigation guidance has been published yet. This vulnerability affects a specific firmware version, so devices running V240425 are at risk. The attack surface includes any exposed device management interfaces accessible remotely.

The impact of CVE-2026-3613 is significant for organizations deploying the Wavlink WL-NU516U1 wireless adapter with the vulnerable firmware. Successful exploitation can lead to arbitrary code execution on the device, allowing attackers to gain control over the network adapter. This could result in interception or manipulation of network traffic, disruption of wireless connectivity, or pivoting into internal networks. Confidentiality is at risk as attackers could eavesdrop or redirect data flows. Integrity and availability are also threatened due to potential device compromise or denial of service. Given the device’s role in network infrastructure, exploitation could facilitate broader network intrusion or lateral movement. The remote, unauthenticated nature of the exploit increases the threat level, especially in environments where these devices are exposed to untrusted networks or the internet. Organizations relying on these adapters for critical connectivity or operating in sensitive sectors face elevated risks of operational disruption and data breaches.

To mitigate CVE-2026-3613, organizations should immediately identify all Wavlink WL-NU516U1 devices running firmware version V240425. Until an official patch is released, restrict remote access to the device management interface by implementing network segmentation and firewall rules to limit access to trusted administrators only. Disable remote management features if not required. Monitor network traffic for unusual activity targeting the /cgi-bin/login.cgi endpoint. Employ intrusion detection systems with signatures for buffer overflow attempts against this device. Consider replacing vulnerable devices with updated hardware or firmware versions once available. Engage with Wavlink support channels for patch timelines and apply updates promptly upon release. Additionally, conduct regular audits of device firmware versions and maintain an inventory to quickly respond to emerging vulnerabilities. Avoid exposing these devices directly to the internet or untrusted networks to reduce attack surface.