PatchSiren cyber security CVE debrief

CVE-2026-13539 Wavlink CVE debrief

CVE-2026-13539 is a stack-based buffer overflow vulnerability in the Wavlink WL-NU516U1-A M16U1_V240425 device. The issue is located in the /cgi-bin/wireless.cgi file, specifically in the sub_407504 function, which handles the Guest_ssid argument in a POST request. This vulnerability allows for remote exploitation and a publicly available exploit exists. The vendor, Wavlink, was contacted and responded professionally, releasing a fixed version of the affected product. Users are advised to upgrade to the patched version to mitigate this vulnerability.

Vendor: Wavlink
Product: WL-NU516U1-A
CVSS: HIGH 7.4
CISA KEV: Not listed in stored evidence
Original CVE published: 2026-06-29
Original CVE updated: 2026-06-29
Advisory published: 2026-06-29
Advisory updated: 2026-06-29

Who should care

Organizations and individuals using the Wavlink WL-NU516U1-A M16U1_V240425 device should prioritize patching this vulnerability. The vulnerability's high CVSS score of 7.4 indicates a significant risk, and the existence of a public exploit increases the urgency for remediation. IT teams responsible for network security and device management should take immediate action to identify and patch affected devices.

Technical summary

The CVE-2026-13539 vulnerability is caused by a stack-based buffer overflow in the sub_407504 function of the /cgi-bin/wireless.cgi file in Wavlink WL-NU516U1-A M16U1_V240425. The overflow occurs due to improper handling of the Guest_ssid argument in POST requests. This vulnerability can be exploited remotely, and a public exploit is available. Successful exploitation could allow an attacker to execute arbitrary code or cause a denial of service. The CVSS:4.0 vector is AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:P/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X.

Defensive priority

High priority should be given to patching CVE-2026-13539 due to its high CVSS score and the availability of a public exploit. Immediate action is necessary to prevent potential remote code execution or denial of service attacks against Wavlink WL-NU516U1-A M16U1_V240425 devices.

Recommended defensive actions

Apply the patched firmware version provided by Wavlink to the affected devices.
Limit access to the /cgi-bin/wireless.cgi interface to trusted networks or users.
Implement network monitoring to detect potential exploitation attempts.
Conduct a thorough inventory of Wavlink WL-NU516U1-A M16U1_V240425 devices within the organization.
Consider implementing compensating controls, such as web application firewalls, to detect and prevent exploitation.

Evidence notes

The CVE-2026-13539 vulnerability details were obtained from the NVD and Vuldb sources. The vulnerability is confirmed to exist in the Wavlink WL-NU516U1-A M16U1_V240425 device. However, some details, such as the exact impact on confidentiality, integrity, and availability, may require further investigation. The vendor's response and patch availability are noted, but additional verification of patch effectiveness may be necessary.

Official resources

This article is AI-assisted and based on the supplied source corpus.