A Critical Patch Update (CPU) is a collection of urgent software fixes released by vendors, such as Oracle, to address security vulnerabilities and bugs in their products. These patches are designed to close security holes that could be exploited by attackers, helping to protect systems and data from unauthorized access or damage. Critical Patch Updates are typically released on a regular schedule and may include multiple fixes bundled together, ensuring users stay protected against the latest threats. Applying these updates promptly is essential for maintaining the security and stability of software environments.