CVE-2026-25857: Tenda G300-F Command Injection via formSetWanDiag

Tenda G300-F router firmware version 16.01.14.2 and prior contain an OS command injection vulnerability in the WAN diagnostic functionality (formSetWanDiag). The implementation constructs a shell command that invokes curl and incorporates attacker-controlled input into the command line without adequate neutralization. As a result, a remote attacker with access to the affected management interface can inject additional shell syntax and execute arbitrary commands on the device with the privileges of the management process.