CVE-2026-2615 is a command injection vulnerability identified in the Wavlink WL-NU516U1 router firmware up to version 20251208. The vulnerability resides in the singlePortForwardDelete function located in the /cgi-bin/firewall.cgi script. Specifically, the del_flag parameter is improperly sanitized, allowing an attacker to inject arbitrary shell commands. This flaw can be exploited remotely without requiring user interaction or authentication, as indicated by the CVSS vector (AV:N/AC:L/AT:N/UI:N/PR:H). The vulnerability impacts the confidentiality, integrity, and availability of the device, as attackers can execute arbitrary commands with high privileges, potentially leading to full device compromise. Although the vendor was contacted early, no patch or mitigation has been released, and a public exploit is available, increasing the risk of exploitation. The vulnerability is classified as high severity with a CVSS 4.0 base score of 8.6. The exploitability is high due to the lack of required user interaction and low attack complexity. The vulnerability affects a widely used consumer and small business router model, which is often deployed in home and enterprise edge networks. The lack of vendor response and patch availability increases the urgency for organizations to implement compensating controls.

The impact of CVE-2026-2615 is significant for organizations using the Wavlink WL-NU516U1 router. Successful exploitation allows remote attackers to execute arbitrary commands on the device with high privileges, potentially leading to full device takeover. This can result in unauthorized access to internal networks, interception or manipulation of network traffic, installation of persistent malware, and disruption of network services. Confidentiality is compromised as attackers can access sensitive network configurations and data. Integrity is affected by the ability to alter device settings or inject malicious code. Availability may be disrupted through denial-of-service or device bricking. The vulnerability's remote exploitability and lack of required user interaction increase the likelihood of widespread attacks. Organizations relying on these devices for perimeter security or network segmentation face elevated risks of lateral movement and data breaches. The absence of vendor patches further exacerbates the threat landscape, necessitating immediate defensive measures.

1. Immediately isolate affected Wavlink WL-NU516U1 devices from untrusted networks, especially the internet, to prevent remote exploitation. 2. Disable remote management interfaces and any unnecessary services exposed to external networks. 3. Implement strict network segmentation to limit access to the vulnerable device from critical internal systems. 4. Monitor network traffic for unusual activity or command injection patterns targeting /cgi-bin/firewall.cgi endpoints. 5. Employ intrusion detection/prevention systems (IDS/IPS) with signatures or heuristics capable of detecting command injection attempts. 6. If possible, replace the affected device with a different model or vendor that has no known vulnerabilities or has been patched. 7. Regularly audit device configurations and firmware versions to ensure no unauthorized changes have occurred. 8. Engage with Wavlink support channels to request official patches or guidance and subscribe to vulnerability advisories for updates. 9. Consider deploying network-level application firewalls to filter malicious HTTP requests targeting the vulnerable CGI script. 10. Educate network administrators about this vulnerability to ensure rapid response and containment in case of detected exploitation attempts.