CVE-2018-5721: Asuswrt-Merlin

High severity, CVSS 8.8. EPSS: 1.9% chance of exploitation in the next 30 days.

Stack-based buffer overflow in the ej_update_variables function in router/httpd/web.c on ASUS routers (when using software from https://github.com/RMerl/asuswrt-merlin) allows web authenticated attackers to execute code via a request that updates a setting. In ej_update_variables, the length of the variable action_script is not checked, as long as it includes a "_wan_if" substring.

Affected products

• Asuswrt-Merlin Asuswrt-Merlin: up to and including 382.1_2

Published 2018-01-17. Last modified 2026-06-17.