Which of the following is a hardware-specific vulnerability?

A firmware version is a hardware-specific vulnerability because firmware is software embedded directly onto hardware devices. Outdated or vulnerable firmware can expose the hardware to exploits, such as privilege escalation or remote code execution, without affecting the operating system or applications running on top of it. Buffer overflows, SQL injection, and cross-site scripting (XSS) are all software-specific vulnerabilities. Buffer overflows exploit memory management issues in applications, SQL injection targets database vulnerabilities in web applications, and XSS exploits client-side script execution in web browsers. These do not directly relate to the underlying hardware's embedded code.