Targeted Codex Prompts for Application Security Audits

X postLoicResource

Loic advises developers against relying on vague instructions like 'check my security' when using Codex, as generalised checks easily miss critical vulnerabilities. He shares four specific prompt templates addressing concrete security domains.

Key points

  1. Broad instructions such as 'find vulnerabilities' often fail to detect vulnerabilities that threaten user data.
  2. Prompt 1 targets data exposure and authorization: mapping API routes and server actions to verify authentication and ownership checks.
  3. Prompt 2 scans repositories for leaked API keys and secrets across client code, public environment variables, committed configs, logs, and build output.
  4. Prompt 3 inspects billing and subscriptions: ensuring prices and permissions are validated server-side and validating webhook signatures.
  5. Prompt 4 audits file upload handling: checking size limits, file types/extensions, executable storage locations, and access controls for private files.

Why it matters

AI coding assistants require clear context and constraints to be effective code auditors. Deconstructing security checks into dedicated, topic-specific prompts dramatically reduces blind spots compared to asking an AI to perform a blanket security review.

Analysis

The author highlights a practical limitation in how developers interact with LLMs for application security. General prompts often yield generic advice or shallow reviews. By focusing prompts on high-risk vectors—broken access controls, credential leaks, payment tampering, and insecure file handling—developers can guide the model to perform systematic, reproducible code reviews.

Original post

Loic

@LDT0545 · 6 November 2026

Stop telling Codex, "check my security." Stop telling Codex, "find vulnerabilities." Stop telling Codex, "make my app secure." A vague security check can miss the issues that put your users' data at risk. Here are 4 prompts you can copy and paste directly:

85 likes1 replies150 bookmarks10.1k views

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More posts in the thread (4)
  1. 1. Find routes that expose user data Review this application for authorization flaws. Map the API routes and server actions that read, create, update, or delete user data. For each one, check whether the server verifies: • The user is authenticated • The user owns the
  2. 2. Check for leaked API keys and secrets Inspect this repository for secrets that may have been exposed. Check: • Client-side code and public environment variables • Committed configuration files and example files • Logs and error messages • Build output or source maps, if
  3. 3. Test payment and subscription access Review how this app decides whether a user has paid access. Check whether: • Prices and permissions are validated on the server • A user can unlock paid features by changing a request or client-side value • Webhook signatures are
  4. 4. Review file uploads Inspect every place where users can upload files. Check for: • Missing file size limits • Unsafe file types or misleading file extensions • Uploads stored where they can be executed • Private files accessible without authorization • Filenames or

Mentioned links

Summary generated by AI (Gemini 3.8 Flash, 7 November 2026). It may contain errors – the original source is authoritative.

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