Introduction Web applications have become an essential part of modern digital life, supporting education, banking, government services, e-commerce, and many other fields. With their widespread use, protecting these applications from security vulnerabilities has become essential to maintaining data confidentiality, system integrity, and service availability. The OWASP Top 10 is one of the most widely recognized references for raising awareness of major web application security risks. It provides a practical framework that helps developers understand common vulnerabilities and reduce security risks throughout the software development process. Common Security Vulnerabilities One of the most common security issues in web applications is broken access control, which may allow users to access functions or data beyond their authorized permissions. Injection vulnerabilities are another major risk and can occur when user-supplied input is handled insecurely, potentially affecting databases or other application components. Other common risks include security misconfiguration, weaknesses in authentication and session management, and the use of outdated software components that contain known vulnerabilities. Addressing these risks requires security to be considered throughout the software development lifecycle rather than only after the application has been completed. Prevention Methods Protecting web applications begins with secure software development, where security requirements are incorporated into every stage of the development lifecycle. The NIST Secure Software Development Framework (SSDF) recommends integrating security practices into software development to reduce vulnerabilities and address their underlying causes. Some important preventive measures include: Validating and securely processing user input. Applying the principle of least privilege to users and systems. Implementing strong authentication and secure session management. Regularly updating software libraries and third-party components. Encrypting sensitive data during storage and transmission. Conducting regular security testing and code reviews. Monitoring security events to detect suspicious activities at an early stage. Conclusion Web application security cannot be achieved through a single security measure. Instead, it requires an integrated approach that begins with system design and continues through development, testing, deployment, and maintenance. By following secure software development principles and utilizing established security references such as OWASP and NIST, developers can significantly reduce security risks and build more reliable and secure web applications. References OWASP Foundation. OWASP Top 10: Web Application Security Risks, 2025. OWASP Foundation. OWASP Cheat Sheet Series – Top 10. National Institute of Standards and Technology (NIST). Secure Software Development Framework (SSDF), SP 800-218, 2022. NIST. Secure Software Development Framework – SSDF Project. Al-Mustaqbal University The First University in Iraq