The vulnerability reveals a stack-based buffer overflow in the Tenda FH451 firmware, triggered by manipulating the wanmode/PPPOEPassword parameter in the /goform/AdvSetWan endpoint. This flaw allows attackers to overflow the stack and potentially execute arbitrary code, thereby compromising the device’s confidentiality, integrity, and availability. The vulnerability is a classic example of the buffer overflow weakness identified by CWE-119 and CWE-121.

The affected system is the Tenda FH451 router running firmware 1.0.0.9. The stack overflow occurs in the sub_3C434 function within the AdvSetWan handler that processes WAN configuration requests.

The flaw receives a CVSS score of 8.7, indicating high severity, but its EPSS score is less than 1%, reflecting a low probability of exploitation in the wild. Because the exploit is publicly available and the vulnerability can be triggered remotely over the network, the risk to an exposed device remains significant. Although the vulnerability is not listed in the CISA KEV catalog, organizations should treat it as critical and apply mitigations promptly.