Secure code reviews need a different lens than the functional code review most teams already run, because the bugs that matter for security, an unvalidated input reaching a database query, a missing authorization check, a hardcoded credential, rarely surface from asking "does this do what the ticket describes." A working checklist, run consistently rather than from memory, closes that gap.
Most engineering teams already do code review as a matter of course, checking readability, test coverage, and whether the logic matches the requirement. Security-focused review layers additional questions on top, and the OWASP Code Review Guide remains one of the more thorough public references for what those questions should be, organized by vulnerability class rather than by code style.
What should reviewers check for input handling?
Every place user input enters the system deserves scrutiny: is it validated against an expected format before use, and is it handled with a safe API rather than concatenated directly into a query, command, or template. This is the root of SQL injection, command injection, and most injection classes generally, and it's the single highest-value category to check consistently, because it's also the category most likely to be missed in a review focused purely on functional correctness. Parameterized queries and prepared statements should be the default; any raw string concatenation into a query deserves a specific question from the reviewer about why.
Output encoding is the counterpart concern, and it's the root cause behind most cross-site scripting vulnerabilities: data rendered back to a user, especially anything sourced from another user's input, needs context-appropriate encoding, HTML encoding for HTML contexts, JavaScript encoding inside script blocks, and so on. A review that only checks input validation and ignores output encoding will miss stored XSS every time.
What should reviewers check for authentication and authorization?
Authorization checks deserve line-by-line attention, not a spot check, because the most damaging real-world flaws are often authorization gaps: an endpoint that checks whether a user is logged in but not whether they're allowed to access the specific resource they're requesting. This is the pattern behind most insecure direct object reference and broken access control findings, and it's genuinely hard to catch with automated tooling alone, since the tool often can't reason about the business logic of who should be allowed to see what. This is exactly where human secure code review earns its keep over purely automated scanning.
Session handling deserves its own check: are session tokens generated with sufficient entropy, invalidated on logout, and scoped correctly, and does the application avoid exposing session identifiers in URLs, where they can leak through referrer headers or browser history.
What should reviewers check for secrets and dependencies?
Hardcoded credentials, API keys, and connection strings committed directly into source are a recurring and entirely preventable finding, and a reviewer should specifically scan diffs for anything resembling a secret before approving, since automated secret-scanning tools miss some patterns and catching it before merge is far cheaper than rotating a credential after it's been exposed in git history.
Dependency changes deserve a look too: a pull request that bumps or adds a third-party library is an opportunity to check whether that library has known vulnerabilities, and whether it's actually necessary versus something already available in the existing dependency tree. This is one area where automated SCA tooling genuinely outperforms manual review, since keeping a mental model of every dependency's current CVE status isn't realistic for a human reviewer.
How does this checklist work alongside automated tooling?
A checklist-driven human review and automated static analysis aren't competing approaches, they cover different ground. Automated SAST/DAST tooling catches pattern-based issues reliably and at scale, injection-prone code shapes, missing encoding, known-bad API usage, across every commit without requiring a human to remember to look. Human review, guided by a checklist like this one, catches the business-logic and authorization gaps that require understanding what the code is supposed to do, not just what it does mechanically. Pairing consistent automated SCA scanning for the dependency layer with checklist-driven human review of the custom logic is the combination that catches the most, since neither approach alone covers the full risk surface.
FAQ
How is secure code review different from a regular code review?
Regular code review checks functional correctness, readability, and test coverage. Secure code review adds a specific lens for injection risks, authorization gaps, secrets, and dependency risk that a purely functional review often overlooks.
Should secure code review replace automated SAST scanning?
No, they're complementary. Automated SAST catches pattern-based issues consistently at scale, while human secure code review is better suited to authorization logic and business-logic flaws that require understanding intent, not just syntax.
What does OWASP's guidance say about secure code review?
The OWASP Code Review Guide organizes review guidance by vulnerability class, injection, authentication, session management, access control, and provides concrete code-level examples for each, making it a useful reference for building an internal checklist.
How long should a secure code review take?
It depends on the change size, but a focused review using a checklist against a typical pull request usually adds modest time over a standard functional review, and that time investment scales far better than the cost of remediating a vulnerability found in production.