A secure code review is a deliberate examination of source code to find security flaws before an application is shipped. A secure code review checklist is a structured list of items you can follow to make sure your review covers everything from authentication logic to dependency management. By consistently using a checklist, developers avoid oversights and improve both the security and readability of their code.
Why should you care about a secure code review checklist? Software flaws are a major cause of breaches. According to the 2024 Verizon Data Breach Investigations Report (DBIR), 14% of breaches involved exploiting vulnerabilities as an initial access step and that figure nearly tripled from the previous year. The Cloud Security Alliance notes that breaches involving exploited vulnerabilities rose by 180% in 2024 and web applications were involved in nearly half of the incidents. When vulnerabilities slip through review, attackers find them first. A repeatable approach keeps teams ahead of attackers and earns users’ trust.
In this article we’ll unpack the goals of secure code review, show how to structure a checklist, walk through a step‑by‑step review process, and share best practices. Whether you lead a large engineering team or work on frontend code yourself, you’ll leave with a concrete secure code review checklist you can put into practice today.
What Is Secure Code Review?
A secure code review can be performed manually, with automated tools, or through a combination of both methods. Manual review involves developers reading each change and discussing it with peers. Automated scanning uses Static Application Security Testing (SAST) and Dynamic Application Security Testing (DAST) tools to find known vulnerability patterns. Each method has distinct strengths and weaknesses.
For a clearer comparison, consider the following:
Aspect | Manual Review | Automated Review (Tools) |
Strengths | - Finds business logic flaws - Detects complex, contextual issues - Low rate of false positives | - Very fast and scalable - Catches common vulnerabilities - Easily integrated into development pipelines |
Weaknesses | - Slow and resource-intensive - Dependent on reviewer expertise - May miss simple, common errors | - Misses business logic and context - Can produce many false positives - Limited to known vulnerability patterns |
Automation is effective for speed and finding common issues, while manual review is superior for uncovering business logic errors that tools are unable to see. This is why a hybrid approach, using tools for broad coverage and manual checks for critical components, is often considered the most effective strategy.
Studies show that structured inspections discover over 60% of defects compared to 25–45% for standard testing. Aetna reportedly cut errors by over 80% and reduced staffing needs by 20% after adopting consistent code reviews.
Secure review doesn’t exist in isolation. Threat modeling helps you identify high‑risk flows before you write a line of code. Secure coding standards, such as the OWASP Secure Coding Practices, give developers baseline rules for input validation, output encoding and session management. Integrating these practices into your software development life cycle (SDLC) means security checks happen alongside feature development, not at the end. A secure code review checklist makes the process repeatable by outlining tasks for each review stage.
Core Goals of a Secure Code Review Checklist
A good checklist should balance quality, security, and maintainability. Here are the core goals:
Improve readability and manage complexity. To enhance code readability and manage complexity, it's best to create smaller pull requests and use consistent formatting. These habits help reviewers better understand the purpose of your changes.
This clarity is also a security matter. Hard-to-read code can hide vulnerabilities, a problem that gets worse in large teams where multiple developers touch the same files. When logic is difficult to follow, security flaws can be missed during the review process.
The benefits are also visible in productivity. Data from Graphite shows that teams with review sizes around 50 lines of code ship features 40% more frequently while maintaining the same standard of quality.
Enforce least privilege. Verify that each module and function has only the permissions it needs. The OWASP checklist urges restricting access to protected URLs, functions and data to authorised users.
Detecting vulnerabilities. Look for injection flaws, broken access control, authentication problems, cryptographic missteps, improper error handling and insecure session management. The OWASP Top Ten warns that broken access control and injection issues occur in 94% of tested applications.
Validate inputs and encode outputs. According to OWASP, all data from untrusted sources should be validated for type, length and range. Output should be encoded for its specific context (HTML, SQL, XML).
Ensure robust error handling and logging. Logs should capture authentication failures, access control failures and tampering attempts without exposing sensitive details. Use generic error pages to avoid leaking stack traces.
Encrypt sensitive data. Use salted hashes and avoid weak algorithms like MD5 or SHA‑1; use AES for encryption and never reuse initialization vectors.
Manage dependencies. Keep libraries up to date and avoid deprecated components. The OWASP Top Ten lists vulnerable and outdated components as a top risk.
Validate configuration and deployment. Ensure test and production configurations are separate, secrets are not hard‑coded and TLS settings are secure.
Secure Code Review Checklist
A solid secure code review checklist is organised into sections so reviewers can work systematically. Here’s a recommended structure:
1) Information Gathering
Identify all external dependencies and frameworks.
Document routes, API endpoints and expected inputs (query params, body fields, headers).
Note any third‑party services or APIs the code calls.
2) Configuration
Confirm there are no hard‑coded secrets or credentials. Environment variables or secrets management tools should be used.
Verify separation between test and production configurations (databases, API keys). Mixing them risks data leaks and unpredictable behaviour.
Check that dependencies are up to date and not deprecated. Use tools like
npm auditorpip‑aand cross‑check with advisories.
3) Secure Transmission
Ensure all traffic carrying sensitive data uses HTTPS or TLS 1.2/1.3. Reject fallback to insecure versions.
Confirm no sensitive tokens, session IDs or passwords appear in URLs, query strings or logs.
4) Authentication & Session Management
Use secure, HTTP‑only,
SameSitecookies for session identifiers.Avoid using HTTP GET for login operations; credentials should be sent via POST.
Verify logout invalidates the session and generates a new session ID on re‑login.
5) Authorization / Access Control
Use centralized authorization checks rather than scattered logic.
Restrict privileged operations by role, ensuring the server enforces these checks on every request. Validate these controls by testing negative scenarios, such as attempting to access administrative functions with a regular user account.
Prompt for re‑authentication before sensitive operations (e.g., a password change or a financial transaction).
6) Input Validation & Output Encoding
Validate input length, type and format on the server side.
Sanitize special characters to prevent injection attacks; adopt allow‑lists instead of block‑lists.
Encode outputs contextually (HTML, JSON, SQL).
7) Error Handling & Logging
Use generic error messages; avoid leaking internal details in responses.
Include who, when and what in logs but sanitize user input so it can’t execute code.
Log authentication attempts, access control failures, and tampering events.
8) Cryptography / Data Encryption
Always use cryptographically strong random values for salts and initialization vectors.
For password hashing, use modern algorithms like Argon2, bcrypt, or PBKDF2. Avoid outdated hash functions such as MD5, SHA-1, or SHA-1-based HMACs.
When encrypting data, prefer AES-128/192/256 with authenticated modes like GCM or CCM.
Prohibit the use of obsolete and insecure algorithms, including RC4, DES, and 3DES.
To implement these practices safely, it is a good idea to use a high-quality, vetted cryptographic library. Good options include Google Tink or libsodium, which help prevent common implementation mistakes.
9) Dependency & Configuration Management
Schedule regular updates for libraries and frameworks. Use
npm audit,yarn audit, orpip‑auditto identify known vulnerabilities.Avoid deprecated or unmaintained libraries; replace them with supported alternatives.
Check deployment settings (CSP headers, secure TLS configuration, file permissions) to ensure secure defaults.
Step‑by‑Step Secure Code Review Process
Here’s a practical process to conduct a thorough review. It combines automation with manual checks and fosters collaboration.
Preparation: Agree on the scope and objectives of the review. Gather the threat model, architecture diagrams and design documents so reviewers understand context.
Submit code: Developers open a pull request (PR) with a clear description of what the change does, why it’s needed and any known risks. Small, focused PRs improve readability.
Run automated scans: Use SAST tools like SonarQube, Checkmarx, or Snyk to catch common issues. DAST tools can test running applications for injection flaws, misconfigurations, or logic errors. It is critical to tune these tools to reduce false positives and improve the signal-to-noise ratio.
Manual review: Reviewers focus on critical areas: authentication flows, authorization checks, session management, error handling and cryptography. They follow the secure code review checklist for each area.
Peer collaboration: Developers discuss findings in comments or pair‑review sessions. Graphite’s data shows that code reviews can reduce errors by more than 80% when adopted consistently.
Remediation and retesting: Developers fix identified issues and rerun scans. In the DBIR, 68% of breaches involved non‑malicious human mistakes. Early remediation prevents those mistakes from going live.
Verification and sign‑off: Once the code passes automated and manual checks, reviewers approve the PR and sign off. Add comments summarizing what was reviewed and any assumptions.
Post‑review documentation: Document findings, actions taken and lessons learned. Add patterns discovered to the checklist for future reviews.
By following this process, your team turns code review into a structured practice rather than a quick glance.
Secure Code Review: Key Best Practices
Here are broader practices to integrate into your development cycle:
Threat model early. Identify potential attackers, assets and entry points at the design stage. This makes review efforts targeted. CISA’s Secure by Design program highlights that products built with security in mind significantly reduce exploitable flaws before release.
Apply secure coding standards. Follow OWASP’s secure coding practices: validate inputs, encode outputs, enforce proper authentication and restrict access.
Balance readability and logic flow. Keep functions small and cohesive. Avoid “spaghetti code” by using descriptive function names and breaking complex logic into smaller pieces.
Manage third‑party libraries. Use known, supported libraries and monitor them for vulnerabilities. The top vulnerabilities list from CISA encourages developers to review high‑priority weaknesses and adopt secure development practices.
Monitor logging. Implement centralized logging. Review logs regularly for abnormal patterns such as repeated failed logins or unexpected privilege escalations.
Watch complexity. Tools like cognitive complexity metrics in ESLint or SonarQube help keep functions understandable. High complexity often hides bugs and security gaps.
Use strong encryption. Follow NIST recommendations: avoid MD5, SHA‑1 and deprecated cipher suites. Use AES and authenticated modes like GCM. Ensure initialization vectors are unique and random.
Tools & Automation Support
Automation complements manual review by catching repetitive and known issues. Some suggested tools include:
SonarQube: An open-source SAST tool that integrates into CI pipelines and flags bugs, code smells, and security hotspots.
Checkmarx: A commercial SAST platform with support for many languages and frameworks.
Snyk: Scans open-source dependencies for known vulnerabilities and license issues. It integrates with GitHub and GitLab.
Codacy: Provides automated code quality and security checks with inline feedback.
Qodo Merge and Bugdar: These hybrid platforms differ from standard SAST tools, which primarily find syntax errors and known vulnerability patterns. By using context-aware scanning, Qodo Merge and Bugdar can identify deeper flaws within the business logic itself. This approach allows them to flag problems like improper transaction sequences or authorization errors that a traditional scanner, unaware of the application's purpose, would miss. These tools help developers focus on more complex problems while automation handles routine checks.
When integrating automated tools, it's important to know they are not silver bullets. They often produce false positives and can miss context. Use them to reduce the manual workload, but always conduct a human review guided by a secure code review checklist.
Bringing It All Together: Sample Secure Code Review Checklist
Below is a condensed example of a secure code review checklist you can adapt. Each row ties a review area to what to check, its security goal, and keywords you might use in code or comments. Avoid long sentences inside the table; keep entries concise.
Area | What to Check | Security Goal |
Information | List dependencies and frameworks; document routes and inputs | Understand attack surface |
Configuration | No hard‑coded secrets; separate test/prod; update packages | Prevent exposure of credentials |
Transmission | Use TLS 1.2/1.3; no sensitive data in URLs/logs | Protect data in transit |
Authentication | Use POST for login; secure cookies; enforce logout | Protect authentication methods |
Authorization | Centralized checks; enforce least privilege | Ensure only authorized actions |
Input & Output | Validate type, length; sanitize; encode outputs | Prevent injection & XSS |
Error Handling | Generic error messages; log but sanitize data | Avoid information disclosure |
Cryptography | Use bcrypt/Argon2; avoid MD5/SHA‑1; unique IVs | Secure password storage |
Dependencies | Regular updates; avoid deprecated libraries | Reduce third‑party risk |
Conclusion
Building software that users trust demands more than functional correctness. Vulnerabilities exploited in the wild are growing quickly, with DBIR data showing a nearly threefold increase in breaches due to exploited flaws. A well‑designed secure code review checklist ensures your team catches issues early, enforces consistent standards and improves developer confidence.
Combine automated scanning with manual review and threat modeling. Follow secure coding standards, use modern cryptography and manage dependencies. Document your process and update the checklist as new threats emerge. When you build security into your development workflow, you protect not just your codebase but also your users’ data and your organisation’s reputation.
FAQs
1) What are the 7 steps to review code?
According to Qodo’s breakdown, the seven steps are: prepare objectives and gather documentation; submit code with context (a pull request); run automated scans (SAST/DAST); perform manual review focusing on sensitive flows; collaborate with peers and gather feedback; fix vulnerabilities and retest; and verify and sign off, documenting results.
2) How do you do a secure code review?
Follow the step‑by‑step process above using a secure code review checklist. Start by understanding the goals and context of the code, then run automated scans, perform manual review focusing on input validation, authentication, access control, error handling, encryption, dependency management and logging. Collaborate with your peers, fix issues, retest and document the outcomes.
3) What should be included in a code review checklist?
Include functional and security checks: readability and complexity; vulnerability detection using automated and manual methods; authentication methods, authorization controls and session management; input validation, output encoding and error handling; cryptography and data protection; dependency management; and logging and monitoring.
4) What is a secure code review (SCR)?
Secure Code Review is a formal process where developers examine source code—manually and with tools—to identify security vulnerabilities before release. A secure code review checklist codifies the areas to inspect: configuration, authentication, validation, cryptography, session logic, logging, dependencies and threat modeling. This structured approach ensures consistent coverage and reduces the risk of introducing exploitable flaws.
