TP-Link Archer AX21 (AX1800) firmware versions before 1.1.4 Build 20230219 contained a command injection vulnerability in the country form of the /cgi-bin/luci;stok=/locale endpoint on the web management interface. Specifically, the country parameter of the write operation was not sanitized before being used in a call to popen(), allowing an unauthenticated attacker to inject commands, which would be run as root, with a simple POST request.
https://thehackernews.com/2024/04/cisco-warns-of-global-surge-in-brute.html?&web_view=true
https://isc.sans.edu/diary/rss/30418
http://packetstormsecurity.com/files/174131/TP-Link-Archer-AX21-Command-Injection.html