An unauthenticated denial-of-service (DoS) vulnerability exists in multiple ZTE router models including H8102E, H168N, H167A, and others. The issue is triggered by sending an oversized application/x-www-form-urlencoded POST request to the router's web management interface, causing it to become unresponsive until rebooted. The vulnerability affects firmware versions prior to 2022, though the supplier claims devices are not vulnerable since March 23, 2021, with operator firmware potentially varying.