The vulnerability resides in the tools_diagnostic function of TRENDnet TEW‑821DAP firmware up to version 1.12B01 and allows an attacker to inject arbitrary operating‑system commands. This can lead to remote code execution on the device, compromising its confidentiality, integrity, and availability. The weakness corresponds to CWE‑77 (OS Command Injection) and CWE‑78 (OS Command Injection via Environment Variable).

Affected hardware is the TRENDnet TEW‑821DAP router, specifically firmware versions up to 1.12B01 that run on the v1.xR hardware revision. That firmware is no longer supported by TRENDnet, which ceased selling the product eight years ago.

The CVSS base score of 5.1 indicates moderate impact. The EPSS score is 1%, which implies a very low but non‑zero probability of exploitation, and the vulnerability is not listed in the CISA KEV catalog, suggesting limited documented exploitation. The known public exploit indicates that an attacker who can reach the device’s diagnostics interface — via network or local management interface — could trigger the injection. The lack of a current support contract and absence of a fixed version means the risk remains unless mitigated through other controls.