Linksys WRT120N tmUnblock.cgi Stack-Based Buffer Overflow Admin Password Reset

A stack-based buffer overflow vulnerability exists in the tmUnblock.cgi endpoint of the Linksys WRT120N wireless router. The vulnerability is triggered by sending a specially crafted HTTP POST request with an overly long TM_Block_URL parameter to the endpoint. By exploiting this flaw, an unauthenticated remote attacker can overwrite memory in a controlled manner, enabling them to temporarily reset the administrator password of the device to a blank value. This grants unauthorized access to the router’s web management interface without requiring valid credentials.