OWASP Top 10 (2025): The Complete Developer Guide

The OWASP Top 10 is a regularly updated ranking of the most critical security risks to web applications, published by the Open Worldwide Application Security Project. It serves as the industry-standard awareness document for developers and security teams, defining the baseline of application security that every organization should address.

The list is compiled from real-world vulnerability data contributed by security firms, bug bounty programs, and application security vendors worldwide. Each category aggregates related Common Weakness Enumerations (CWEs) and is ranked by a combination of exploitability, prevalence, detectability, and technical impact.

For developers, the OWASP Top 10 is not a compliance checklist—it is a prioritization framework. It answers the question: "If I can only address a limited number of vulnerability classes, which ones matter most?" Regulatory frameworks like PCI-DSS, SOC 2, and ISO 27001 reference the OWASP Top 10 as a minimum standard for application security assessments.

The most recent major revision reorganized categories to reflect how modern applications are built, adding categories for Insecure Design, Software and Data Integrity Failures, and Server-Side Request Forgery.

A01: Broken Access Control

Access control enforces policies so users cannot act outside their intended permissions. Failures include IDOR (Insecure Direct Object References), path traversal, missing function-level access checks, and CORS misconfiguration. This moved to the #1 position due to its prevalence in modern applications.

A02: Cryptographic Failures

Formerly "Sensitive Data Exposure," this category focuses on the root cause: weak or missing cryptography. It covers data transmitted in cleartext, deprecated algorithms (MD5, SHA-1, DES), hardcoded keys, and missing encryption for sensitive data at rest or in transit.

A03: Injection

Injection occurs when untrusted data is sent to an interpreter as part of a command or query. This includes SQL injection (CWE-89), XSS (CWE-79), command injection (CWE-78), NoSQL injection, and LDAP injection. Parameterization and input validation are the primary defenses.

A04: Insecure Design

A new category distinguishing design-level flaws from implementation bugs. Insecure design means the application architecture lacks threat modeling, secure design patterns, or reference architectures. No amount of perfect implementation fixes a fundamentally insecure design.

A05: Security Misconfiguration

Covers missing security hardening, unnecessary features enabled, default credentials, overly permissive cloud configurations, verbose error messages, and missing security headers. Also includes XXE vulnerabilities caused by default XML parser settings.

A06: Vulnerable and Outdated Components

Applications using libraries, frameworks, or dependencies with known CVEs. This applies to direct and transitive dependencies across npm, pip, Maven, and Go modules. Automated dependency scanning and SBOM generation are essential defenses.

A07: Identification and Authentication Failures

Formerly "Broken Authentication." Covers weak password policies, credential stuffing without rate limiting, session fixation, missing multi-factor authentication, and improper session management including predictable session tokens.

A08: Software and Data Integrity Failures

A new category covering insecure CI/CD pipelines, unsigned updates, and insecure deserialization. Applications that pull code or data from untrusted sources without verifying integrity are vulnerable to supply chain attacks.

A09: Security Logging and Monitoring Failures

Insufficient logging of security-relevant events (logins, access control failures, input validation failures) delays breach detection. Without monitoring, attackers operate undetected for months—the average breach detection time exceeds 200 days.

A10: Server-Side Request Forgery (SSRF)

SSRF occurs when a server fetches a URL supplied by an attacker without validation. In cloud environments, this exposes internal metadata services containing credentials. The Capital One breach (2019) demonstrated the catastrophic impact of SSRF in cloud infrastructure.

The OWASP Top 10 matters because it reflects where real breaches happen. These are not theoretical risks—they are the vulnerability classes most frequently exploited in production applications across every industry.

For development teams, OWASP provides a shared vocabulary. When a security engineer flags a finding as "A03: Injection" or "A01: Broken Access Control," every team member understands the severity and category without lengthy explanation. This shared language accelerates triage and remediation.

From a compliance perspective, most security audits and penetration test reports reference OWASP categories. Teams that proactively address the Top 10 find fewer surprises in audits, reduce remediation costs, and spend less time on post-audit scrambles.

The most effective way to address OWASP coverage is to integrate automated static analysis into the development workflow—catching injection, misconfiguration, and cryptographic failures at the pull request stage rather than in production.

CodeSlick covers 95% of the OWASP Top 10 (2025) through 294 security checks across JavaScript, TypeScript, Python, Java, and Go. Analysis completes in under 3 seconds.

• A01 Broken Access Control: Path traversal, IDOR patterns, CORS misconfiguration, missing authorization checks
• A02 Cryptographic Failures: Weak algorithms, hardcoded secrets (38 patterns), missing encryption
• A03 Injection: SQL injection, XSS, command injection, NoSQL injection, code injection across all 5 languages
• A05 Security Misconfiguration: XXE, missing headers, debug mode, default credentials
• A06 Vulnerable Components: Dependency scanning (npm, pip, Maven, Go modules), malicious package detection (66 packages), SBOM generation
• A08 Integrity Failures: Insecure deserialization, unsafe eval patterns
• A10 SSRF: Unvalidated URL fetching, cloud metadata access patterns

Every finding includes CWE mapping, CVSS 3.1 scoring (range 3.1–9.8), and AI-powered fix suggestions. CodeSlick runs on every pull request via the GitHub App, on every commit via the CLI, and on-demand in the free web scanner.