CVE-2026-3613 in WL-NU516U1
Summary
by MITRE • 03/06/2026
A vulnerability was identified in Wavlink WL-NU516U1 V240425. This vulnerability affects the function sub_401A0C of the file /cgi-bin/login.cgi. Such manipulation of the argument ipaddr leads to stack-based buffer overflow. It is possible to launch the attack remotely. The exploit is publicly available and might be used. The vendor was contacted early about this disclosure.
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Analysis
by VulDB Data Team • 03/11/2026
The vulnerability CVE-2026-3613 represents a critical stack-based buffer overflow in the Wavlink WL-NU516U1 V240425 device firmware, specifically within the sub_401A0C function located in the /cgi-bin/login.cgi file. This flaw arises from improper input validation when processing the ipaddr argument, creating an exploitable condition that allows attackers to manipulate memory layout through carefully crafted input parameters. The vulnerability exists at the application layer within the web interface component of the network device, making it particularly dangerous as it can be leveraged by remote attackers without requiring physical access or elevated privileges.
The technical implementation of this vulnerability stems from a classic buffer management error where the application fails to properly bounds-check user-supplied input before copying it into a fixed-size stack buffer. This function appears to handle IP address validation or logging operations but does not adequately validate the length or content of the ipaddr parameter, allowing an attacker to overflow the allocated buffer space and potentially overwrite adjacent stack memory including return addresses and function pointers. The use of a stack-based buffer overflow provides attackers with the capability to execute arbitrary code or cause denial of service conditions, depending on the specific memory corruption patterns and exploitation techniques employed.
Operationally, this vulnerability presents a significant risk to network infrastructure security as it enables remote code execution capabilities without authentication requirements. The publicly available exploit demonstrates that this vulnerability is not theoretical but actively being leveraged by threat actors in the wild. Network administrators and security professionals must recognize that this vulnerability affects network devices that are often deployed in critical infrastructure environments where unauthorized access could lead to complete system compromise, data exfiltration, or network disruption. The impact extends beyond individual device compromise to potentially enable lateral movement within network segments where these devices are deployed.
Mitigation strategies for CVE-2026-3613 should prioritize immediate firmware updates from the vendor, as this vulnerability represents a known exploit that has already been made available to the public. Organizations should implement network segmentation to limit access to affected devices and monitor for exploitation attempts through intrusion detection systems. The vulnerability aligns with CWE-121 stack-based buffer overflow classification and could be mapped to ATT&CK technique T1210 exploitation of remote services, highlighting the need for comprehensive security measures including network monitoring, access control enforcement, and regular vulnerability assessments. Security teams should also consider implementing temporary network controls such as firewall rules restricting access to the affected web interface and conducting thorough network scans to identify all potentially affected devices within their infrastructure.