Elixir Security Review

Reviews Elixir code for security vulnerabilities including code injection, atom exhaustion, and secret handling. Use when reviewing code handling user input, external data, or sensitive configuration.

Quick Reference

Issue Type	Reference
Code.eval_string, binary_to_term	references/code-injection.md
String.to_atom dangers	references/atom-exhaustion.md
Config, environment variables	references/secrets.md
ETS visibility, process dictionary	references/process-exposure.md

Review Checklist

Critical (Block Merge)

• No Code.eval_string/1 on user input
• No :erlang.binary_to_term/1 without :safe on untrusted data
• No String.to_atom/1 on external input
• No hardcoded secrets in source code

Major

• ETS tables use appropriate access controls
• No sensitive data in process dictionary
• No dynamic module creation from user input
• Path traversal prevented in file operations

Configuration

• Secrets loaded from environment
• No secrets in config/*.exs committed to git
• Runtime config used for deployment secrets

Valid Patterns (Do NOT Flag)

• String.to_atom on compile-time constants - Atoms created at compile time are safe
• Code.eval_string in dev/test - May be needed for tooling
• ETS :public tables - Valid when intentionally shared
• binary_to_term with :safe - Explicitly safe option used

Context-Sensitive Rules

Issue	Flag ONLY IF
String.to_atom	Input comes from external source (user, API, file)
binary_to_term	Data comes from untrusted source
ETS :public	Contains sensitive data

Hard gates (before reporting)

Complete in order for each finding you intend to report. Do not advance until the pass condition is satisfied.

1. Location artifact — The finding includes [FILE:LINE] (or a line range) that you copied from the current file contents; the path resolves in this repo.
2. Scope read — You read the full surrounding function or module section that contains the flagged code, not only a diff hunk or summary.
3. External-data claim (only if the finding depends on “user/untrusted input”) — You can name one concrete ingress (for example conn.params, Jason.decode!/1 result, uploaded file path, message from another node) or you drop the finding because the value is compile-time, test-only, or internal per Context-Sensitive Rules.
4. Protocol — Pre-report steps in review-verification-protocol are satisfied for this item (no finding if they are not).

Before Submitting Findings

Use the issue format: [FILE:LINE] ISSUE_TITLE for each finding.

Hard gate 4 requires review-verification-protocol; use it as the full pre-report checklist and issue-type verification (it extends beyond this skill’s summary).