Security Review

Security Review

A focused checklist for catching real vulnerabilities in a change set. Apply it to the diff first (the lines that actually changed and the code they call), then widen only if a finding points elsewhere. Report findings; do not rewrite code unless explicitly asked.

Threat checklist

• Injection — untrusted input flowing into SQL, shell, OS commands, eval, template engines, or LDAP. Look for string concatenation instead of parameterized queries / argument arrays.
• XSS — user data rendered into HTML/JS/DOM without escaping. Check innerHTML, dangerouslySetInnerHTML, unescaped template interpolation.
• AuthN / AuthZ — missing authentication, missing ownership/permission checks, IDOR (acting on an object by id without verifying the caller owns it), privilege escalation, trusting client-supplied roles.
• Secrets — hardcoded API keys, tokens, passwords, private keys, or connection strings; secrets logged or committed. Should come from env/secret store, never source.
• Path traversal / file access — user-controlled paths joined without normalization/allow-listing (../ escapes, symlink following).
• SSRF — server-side requests to a user-supplied URL/host without allow-listing; can reach internal metadata endpoints.
• Deserialization / parsing — untrusted data fed to unsafe deserializers (pickle, native YAML loaders, Java/PHP object deserialization).
• Crypto — weak/auto algorithms (MD5/SHA1 for passwords), hardcoded IVs, ECB mode, missing TLS verification, predictable randomness for tokens.
• Sensitive data exposure — PII/secrets in logs, error messages, or API responses; verbose stack traces leaked to clients.
• Dependencies — newly added packages: are they reputable, pinned, and free of known CVEs? Avoid typosquats. For supply-chain verification, use gh attestation (see the gh-cli skill).
• Resource & DoS — unbounded loops, unbounded request/body sizes, missing timeouts, regex catastrophic backtracking (ReDoS).
• Race conditions / TOCTOU — check-then-act on files, balances, or auth state without locking.

Method

1. Identify the trust boundary: where does untrusted input enter, and where does it reach a sink (DB, shell, filesystem, network, HTML)?
2. Trace each tainted value from source to sink; a vuln exists when it reaches a dangerous sink without validation/encoding/parameterization.
3. Prefer allow-lists over deny-lists; prefer library-provided escaping and parameterization over manual sanitization.
4. Only flag issues you can justify with a concrete exploit path — no speculative or style-only noise.

Report format

critical/major are blockers; minor/nit are suggestions. Severity levels match the code-review skill (critical/major = blockers; minor/nit = suggestions).

For each finding:

[severity: critical|major|minor|nit] <title>
location: path/to/file.ext:LINE
issue: <what is wrong and the input that triggers it>
impact: <what an attacker gains>
fix: <the minimal concrete remediation>

Order findings by severity. If you reviewed the change and found nothing actionable, say so explicitly rather than padding with low-value notes.