A zero-day exploit is a type of security vulnerability that is unknown to the software vendor or developer. It is also called a zero-day attack or zero-day vulnerability because it is exploited on the same day the vulnerability is discovered. The vulnerability can be used to gain unauthorized access to a system or application, allowing attackers to gain control of the system or application, or to install malicious software.

Zero-day exploits are a serious security threat, as they can be used to gain access to sensitive data or launch malicious attacks. They can also be used to exploit weaknesses in applications or operating systems, allowing attackers to take control of the system or application and potentially gain access to sensitive data. In some cases, attackers can even use the exploit to cause widespread damage to the system or application.

Zero-day exploits can be difficult to detect and remediate. Organizations must be vigilant in monitoring their systems and applications for any signs of zero-day vulnerabilities. They must also have an established security policy in place to ensure any discovered vulnerabilities are quickly patched or mitigated. Regular vulnerability assessments and penetration testing can also help organizations identify and address zero-day exploits before they can be exploited by attackers.