CVE-2018-5721

Severity: high (CVSS 8.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 1.9% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2018-01-17 · updated 2026-06-17
Weakness: CWE-787

Description

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: through 382.1_2

References

http://www.w0lfzhang.com/2018/01/17/ASUS-router-stack-overflow-in-http-server/
http://www.w0lfzhang.com/2018/01/17/ASUS-router-stack-overflow-in-http-server/

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