Security code review is a systematic examination of application source code to identify security vulnerabilities, logic flaws, and insecure coding patterns before software reaches production. It combines automated static analysis (SAST) with manual expert review to find weaknesses that testing alone cannot reliably detect, including authentication bypasses, authorization flaws, cryptographic misuse, and injection vulnerabilities.
Code review is a shift-left practice, catching vulnerabilities at the earliest and cheapest point in the development lifecycle. It is a core component of secure software development lifecycle (SSDLC) programs.
Automated SAST tools like Semgrep, SonarQube, and Checkmarx scan codebases for known vulnerability patterns, taint flows, and CWE-classified weaknesses. These tools integrate into CI/CD pipelines to provide immediate feedback on pull requests. However, automated tools produce false positives and miss business logic flaws, making manual review essential.
Manual security code review focuses on high-risk areas: authentication and session management, authorization checks, input validation and output encoding, cryptographic implementations, error handling and logging, and third-party component usage. Reviewers trace data flows from untrusted inputs through processing logic to sensitive operations, identifying points where sanitization or validation is missing.
Effective code review programs use risk-based prioritization to focus manual effort on the most critical components. They maintain secure coding guidelines specific to the organization's tech stack, provide developers with actionable remediation guidance, and track metrics like defect density and time to remediation. Code review findings feed back into developer training programs.
Security code review prevents vulnerabilities from reaching production, where remediation costs 30 to 100 times more than during development. It builds security knowledge within development teams and creates a culture of security ownership. Organizations with mature code review programs experience fewer production vulnerabilities and faster incident response.