Injection is a common cybersecurity vulnerability that occurs when an attacker is able to inject malicious code or commands into an input field or parameter of a web application. This can lead to unauthorized access, data theft, or system compromise. Common types of injection attacks include SQL injection, where an attacker manipulates a database query, and cross-site scripting (XSS), where an attacker injects malicious scripts into a website. Injection attacks can be mitigated through proper input validation, parameterized queries, and other security measures.