Command injection is a critical security flaw in Python applications that can expose them to unauthorized command execution, potentially leading to data breaches, system compromise, and other malicious activities. It occurs when an attacker can execute arbitrary system commands by injecting them into a vulnerable program, often through unsanitized user input or dynamic command construction. Common scenarios leading to command injection vulnerabilities include passing unsanitized user input to system commands, using the subprocess module with shell=True, and dynamically constructing command strings without proper checks and validation. To mitigate these risks, developers should implement proper input validation and sanitization, use parameterized queries and prepared statements, avoid using shell=True with the subprocess module unless necessary, safely handle user input and external commands, and leverage security tools and frameworks like Snyk to detect and fix vulnerabilities early in the development lifecycle. By incorporating these guidelines into their development process, developers can protect their Python applications from command injection vulnerabilities and ensure the overall resilience of their software.