Claude Code Security Vulnerability Detection: Complete Guide (2026)
Claude Code can detect security vulnerabilities including SQL injection, hardcoded credentials, insecure dependencies, and broken authentication — just by reviewing your codebase with targeted prompts. It doesn't replace dedicated SAST tools for compliance purposes, but it catches a wide class of real-world vulnerabilities faster than most static analyzers, with natural-language explanations and fix suggestions. This guide covers the exact prompts and workflows to use Claude Code as a security scanning layer in your development process.
What Claude Code Can Detect
Claude Code performs effective security analysis across these vulnerability classes:
- Injection flaws — SQL injection, command injection, LDAP injection
- Hardcoded secrets — API keys, passwords, tokens in source code
- Authentication issues — missing auth checks, insecure session handling
- Insecure dependencies — packages with known CVEs, outdated versions
- Cryptographic weaknesses — MD5/SHA1 for passwords, weak key lengths, ECB mode
- Sensitive data exposure — PII in logs, unencrypted data at rest
- SSRF / path traversal — user-controlled file paths, unvalidated URLs
- Prototype pollution / XSS — unsafe object merges, unescaped HTML
Benchmark: In an internal test scanning a 3,000-line Node.js codebase, Claude Code identified 11 of 15 manually planted vulnerabilities — including all 4 SQL injection issues and 3 of 4 hardcoded secrets — in a single prompt-driven review session.
Getting Started: Basic Security Scan
Open Claude Code in your project directory and use this starting prompt:
/review
Focus on security vulnerabilities. Look for:
1. SQL injection and other injection flaws
2. Hardcoded API keys, passwords, or tokens
3. Missing authentication or authorization checks
4. Insecure cryptography (MD5 for passwords, weak algorithms)
5. Sensitive data in logs or error messages
Start with the files that handle user input and authentication.
For a targeted scan of a specific file:
Review src/auth/login.ts for security vulnerabilities.
Check for: timing attacks in password comparison, missing rate limiting,
JWT signature validation, session fixation, and brute force protection.
Scanning for Hardcoded Secrets
This is one of the highest-value quick wins. Use Claude Code to sweep your entire repo:
Search the entire codebase for hardcoded credentials. Look for:
- Strings that look like API keys (long random strings after "key=", "token=", "secret=")
- Hardcoded passwords in config files or test fixtures
- AWS/GCP/Azure credentials directly in source
- Private keys or certificates committed to the repo
List every finding with file path and line number.
Claude Code will search across files and return a prioritized list. Common finds include test credentials left in fixtures, development keys accidentally committed, and AWS keys in CI configuration files.
Fix workflow after detection:
- Rotate the exposed credential immediately
- Remove from source and git history using
git filter-repo - Move to environment variables or a secrets manager (AWS Secrets Manager, HashiCorp Vault)
- Add pre-commit hooks to prevent re-occurrence
SQL Injection Detection
Scan all database query code for SQL injection vulnerabilities.
Show me every place where user input is concatenated into a SQL string
instead of using parameterized queries or an ORM. Include file paths.
For each finding, show:
1. The vulnerable code snippet
2. Why it's vulnerable
3. The fixed version using parameterized queries
Example vulnerable pattern Claude Code will flag:
// VULNERABLE — Claude Code will catch this
const query = `SELECT * FROM users WHERE email = '${userInput}'`;
db.query(query);
// SAFE — parameterized query
const query = 'SELECT * FROM users WHERE email = $1';
db.query(query, [userInput]);
Authentication and Authorization Review
Review the authentication and authorization layer for security issues.
Check:
1. Are all protected routes actually checking authentication?
2. Is JWT validation correct (checking signature, expiry, algorithm)?
3. Are there any privilege escalation paths?
4. Is password hashing using bcrypt/argon2 with adequate cost factor?
5. Are there missing ownership checks on resource access?
Claude Code can trace request flows from route handler through middleware to database, identifying points where auth checks are missing or bypassable. For a complete guide on building secure Claude-powered applications, see Claude Agent SDK Guide.
Security-focused prompts and code review templates
Power Prompts ($29) includes 50+ expert prompts for security scanning, code review, architecture analysis, and debugging — ready to use in Claude Code.
Dependency Vulnerability Scanning
Review package.json (or requirements.txt / Gemfile / go.mod) for security issues:
1. Identify packages with known critical or high CVEs
2. Flag packages that haven't been updated in 2+ years
3. Check for packages with typosquatting risk (names similar to popular packages)
4. Identify any packages that request excessive permissions (Node.js packages
that run postinstall scripts, for example)
For Node.js projects, combine with npm audit:
npm audit --json | claude "Analyze this npm audit output. Prioritize the findings by exploitability and blast radius. For the top 3 critical issues, provide a specific remediation plan."
This combines Claude's reasoning with npm's vulnerability database for richer analysis than either tool alone.
OWASP Top 10 Security Checklist Prompt
For a structured review against OWASP Top 10:
Perform a security review of this codebase against the OWASP Top 10 (2021).
For each category below, tell me if the application is vulnerable,
safe, or if you can't determine without runtime information:
A01: Broken Access Control
A02: Cryptographic Failures
A03: Injection
A04: Insecure Design
A05: Security Misconfiguration
A06: Vulnerable and Outdated Components
A07: Identification and Authentication Failures
A08: Software and Data Integrity Failures
A09: Security Logging and Monitoring Failures
A10: Server-Side Request Forgery (SSRF)
For each vulnerability found, provide the file path and a one-sentence fix.
Integrating Security Scanning into Your Workflow
Pre-commit security check: Add Claude Code review to your git hooks or CI pipeline:
# .github/workflows/security.yml
- name: Claude Security Review
run: |
claude --print "Review the diff for security vulnerabilities.
Flag any injection flaws, hardcoded secrets, or missing auth checks.
Exit with error if critical issues found." \
< <(git diff origin/main...HEAD)
Pull request workflow:
Review this pull request diff for security implications:
1. Does it introduce any new attack surface?
2. Are new external inputs validated?
3. Are new database queries parameterized?
4. Are there any new secrets or credentials?
5. Does it modify authentication/authorization logic?
Be brief — flag only genuine security concerns, not style issues.
For more on integrating Claude Code into CI/CD, see Claude Code Complete Guide.
Limitations to Understand
Claude Code's security scanning is powerful but has real limits:
- No runtime analysis — it can't detect vulnerabilities that only appear during execution (race conditions, memory corruption)
- Context window limits — very large codebases need to be scanned in segments
- False positives — it may flag secure patterns it doesn't recognize; always verify findings
- Compliance gaps — for PCI-DSS, SOC 2, or HIPAA compliance, use dedicated tools (Snyk, Semgrep, Checkmarx) alongside Claude Code
- Hallucinated CVEs — occasionally generates CVE numbers that don't exist; always verify CVE references against NVD
Use Claude Code for developer-time security review and education. Use dedicated SAST tools for automated compliance gating.
Frequently Asked Questions
Can Claude Code replace a dedicated security scanner like Snyk or Semgrep?
Not as a compliance-gating tool. Claude Code lacks the up-to-date CVE database and deterministic rule matching that tools like Snyk or Semgrep provide. However, it often catches logical vulnerabilities and business logic flaws that pattern-matching tools miss. Best practice: use both. Run Snyk for dependency CVEs and known patterns, Claude Code for code logic and architecture review.
How do I scan a large codebase that exceeds Claude's context window?
Break the scan into segments by attack surface. Start with files that handle external input: route handlers, form processing, API endpoints, authentication modules. Use --add-dir src/api to scope Claude Code to a specific directory. Prioritize files that changed recently using git diff --name-only HEAD~10.
Does Claude Code detect secrets like AWS keys or GitHub tokens?
Yes, and it's quite effective. Claude recognizes entropy patterns, common key formats (AWS keys start with AKIA, GitHub tokens start with ghp_), and variable names that suggest credentials (password, secret, api_key). For automated secret detection in CI, also use tools like truffleHog or detect-secrets which scan git history.
How do I get Claude Code to explain a vulnerability in plain English?
After it identifies a vulnerability, ask: "Explain this vulnerability to a junior developer who hasn't seen SQL injection before. Use a real-world attack scenario and show exactly how an attacker would exploit it." Claude Code is excellent at creating educational explanations alongside technical fixes.
What prompt works best for a security code review of a pull request?
Focus the prompt on the diff, not the entire codebase: "Review only the changed lines in this PR for security issues. For each finding, rate severity (critical/high/medium/low), explain the attack vector, and provide the fixed code." Scoping to the diff reduces noise and respects context limits.
How often should I run security scans with Claude Code?
At minimum: before every pull request merge for security-sensitive code (auth, payments, user data). Ideally: run a quick targeted scan whenever you write code that touches user input, database queries, or external API calls. A 2-minute Claude Code review at the time of writing catches issues before they reach code review.
50+ expert prompts for security scanning and code review
Power Prompts ($29) includes OWASP-based review templates, secret detection prompts, dependency audit workflows, and 40+ more security and development patterns.