Zyxel EMG2926 routers contain a command injection vulnerability located in the diagnostic tools, specifically the nslookup function. A malicious user may exploit numerous vectors to execute malicious commands on the router, such as the ping_ip parameter to the expert/maintenance/diagnostic/nslookup URI.
Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.
CWE-78
https://www.zyxel.com/global/en/support/security-advisories/zyxel-security-advisory-for-command-injection-vulnerability-in-emg2926-q10a-ethernet-cpe, https://www.zyxelguard.com/Zyxel-EOL.asp