This indicates an attack attempt against a Code Injection vulnerability in ZyXEL P660HN-T router.
The vulnerability is due to an error when the vulnerable software handles a maliciously crafted HTTP request. A remote attacker may be able to exploit this to execute arbitrary code on the affected systems.
ZyXEL P660HN-T v1
System Compromise: Remote attacker can gain control of vulnerable systems.
Currently we are unaware of any vendor supplied patch for this issue.