What Is the OWASP Top 10? A Guide to Web Application Security

OWASP Top 10 is a guide that outlines major security risks in web applications and helps developers build more secure software. In this article, you will learn what OWASP Top 10 is, which security risks are included in the 2025 list, and the fundamental practices that can help reduce these risks in software projects.

What Is OWASP Top 10?

OWASP Top 10 is an awareness document published by the Open Worldwide Application Security Project (OWASP), an organization focused on open-source application security initiatives. It classifies prominent security risks in web applications and helps software teams understand these risks.

The guide is not intended solely for cybersecurity professionals. Backend and frontend developers, software architects, test engineers, and technical team leaders can also benefit from OWASP Top 10.

The 2025 edition of OWASP Top 10 is the latest published version. Compared with the previous 2021 list, some category names and scopes have changed. Therefore, it is important to check which version is being used when reviewing security documentation.

Why Is OWASP Top 10 Important?

Web applications interact with user information, accounts, and various business processes. Security vulnerabilities can expose this data to unauthorized individuals, disrupt system operations, or enable applications to be misused.

OWASP Top 10 helps development teams assess security issues more systematically. However, addressing the risks on the list does not guarantee that an application is completely secure. The guide is one of the starting points for a more comprehensive application security process.

What Security Risks Are Included in OWASP Top 10:2025?

OWASP Top 10:2025 groups major web application security risks into 10 categories. The following sections explain what each category means and what developers should consider during software development.

1. What Is Broken Access Control?

Access control determines which data and operations users are allowed to access. When these controls are not implemented correctly, users may gain access to information beyond their permissions or perform unauthorized actions.

For example, allowing a regular user to perform an operation reserved for administrators falls into this category. To prevent such issues, authorization checks should be performed on the server side, and each request should be validated to ensure that the user has permission to perform the requested operation.

2. What Is Security Misconfiguration?

Security misconfiguration occurs when an application or its underlying infrastructure operates with insecure settings. Examples include leaving unnecessary features enabled, failing to change default accounts, or exposing sensitive information through error messages.

Developers should use secure default settings, disable unnecessary services, and prevent development environment configurations from being transferred to production without proper review.

3. What Are Software Supply Chain Failures?

The software supply chain includes the libraries, packages, development tools, build processes, and deployment components used by an application. Security issues anywhere in this chain can create risks, even when the application itself does not contain a direct vulnerability.

It is important to obtain dependencies from trusted sources, track their versions, and protect build processes. Teams should also regularly review the packages they use and minimize unnecessary dependencies.

4. What Are Cryptographic Failures?

Cryptographic failures occur when encryption methods or key management practices used to protect sensitive information are inadequate. Data security can be compromised when user passwords, personal information, and session data are not properly protected.

To reduce these risks, developers should use up-to-date and reliable cryptographic methods, encrypt sensitive data appropriately, and avoid storing secret keys in source code.

5. What Is Injection?

Injection vulnerabilities can occur when an application fails to process untrusted input appropriately. In cases such as SQL injection, user input may cause database queries to be interpreted in unexpected ways.

Using parameterized queries, validating input according to its intended context, and encoding output correctly can help reduce these risks. Never treating user input as inherently trustworthy is a fundamental secure software development practice.

6. What Is Insecure Design?

Insecure design occurs when security requirements are not adequately addressed during the planning and design stages of an application. Even if the code functions correctly, a system can contain significant risks if security controls were not considered from the beginning.

It is important to assess potential threats before development begins, define user permissions, and establish security requirements for critical operations. Security should not be left solely to testing performed after development.

7. What Are Authentication Failures?

Authentication is the process of verifying that a user is who they claim to be. Weak password policies, improper session management, or inadequate authentication mechanisms can lead to unauthorized account access.

To reduce these risks, developers should implement secure session management, use multifactor authentication where appropriate, and store passwords using reliable methods.

8. What Are Software or Data Integrity Failures?

This category concerns inadequate controls for maintaining the integrity of software and data. Unverified updates, components obtained from untrusted sources, and unprotected deployment processes can put data integrity at risk.

The origin of software packages and updates should be verified, integrity checks should be applied to critical files, and appropriate security controls should be incorporated into deployment processes.

9. What Are Security Logging and Alerting Failures?

Security logs help teams investigate events that occur within an application. When important events are not recorded or alerting mechanisms for suspicious activities are missing, security issues may go unnoticed for too long.

Authentication failures, authorization violations, and unexpected system events should be logged appropriately. Developers should also ensure that logs do not contain sensitive information such as passwords, access keys, or unnecessary personal data.

10. What Is Mishandling of Exceptional Conditions?

This category concerns an application's inability to behave securely when unexpected conditions, errors, or edge cases occur. Uncontrolled exceptions, incorrect fallback behavior, or failure to release resources properly can affect an application's reliability and security.

Developers should design appropriate error-handling behavior, manage exceptions correctly, and avoid exposing sensitive system details to users. They should also test scenarios involving timeouts, failed operations, and unexpected input.

How Can Developers Use OWASP Top 10 in Their Projects?

OWASP Top 10 provides a starting framework for incorporating security controls into the software development lifecycle. Rather than reviewing the list only at the end of a project, teams can use it during requirements definition, coding, testing, and deployment to establish a more systematic approach.

The following steps can be applied to a project:

• Define requirements: Identify user data, access permissions, and the systems that need protection.
• Write secure code: Adopt practices such as input validation, parameterized queries, secure session management, and proper authorization.
• Review dependencies: Track the versions of libraries in use and check for known security issues.
• Automate testing: Integrate code analysis, dependency scanning, and appropriate security tests into the development process.
• Monitor errors and events: Establish suitable logging and alerting mechanisms.
• Conduct regular reviews: Reassess security controls as new features are introduced, infrastructure changes, and threats evolve.

These practices help teams identify application risks earlier. However, OWASP Top 10 alone is not a substitute for comprehensive security testing, threat modeling, or professional security assessments.

What Is the Difference Between OWASP Top 10 and OWASP ZAP?

OWASP Top 10 and OWASP ZAP serve different purposes. Top 10 is a guide that describes major application security risks. OWASP ZAP is an open-source security testing tool that can be used to assess the security of web applications.

Developers can use OWASP Top 10 to understand risks and plan development processes. Tools such as ZAP can be used to perform authorized and controlled security checks in appropriate testing environments.

OWASP Top 10 is an important starting point for understanding web application security and developing secure coding habits. Learning the 2025 categories, assessing security risks from design through deployment, and conducting regular tests can help you build more reliable applications.