Review code changes for security

Use a security change review when you need evidence about regressions introduced by one Git-backed change set. The workflow reviews every changed source-like file and directly supporting code without turning the task into a general repository audit.

If you want to scan a full repository instead of a specific change, see Run a security scan.

Run a manual review

For uncommitted changes, send:

Use $codex-security:security-diff-scan to review my current uncommitted changes for security regressions.

For a commit or branch range, identify both ends when needed:

Use $codex-security:security-diff-scan to review the changes from origin/main to HEAD for security regressions. Focus on authentication, authorization, input handling, filesystem access, network requests, and secrets.

You can also name a pull request when its base and head revisions are available in the local checkout.

Confirm the change in setup

The workflow doesn’t check out another branch or change the selected working tree. If a requested revision isn’t available locally, fetch it before the review or provide a locally available base and head.

Act on findings

After reviewing the results, fix and verify an accepted finding or export and track findings.

Automate reviews in CI/CD

You can run a change review from any CI/CD system that can check out the target revisions and invoke the Codex CLI without interaction. Resolve the exact base and head revisions, use a read-only sandbox, save the Markdown result, and publish it through your CI/CD system.

GitHub Actions example

The following GitHub Actions workflow is one implementation of this pattern. It uses openai/codex-action to install the Codex CLI and run codex exec with a read-only sandbox. It produces a Markdown review for every in-scope pull request.

Before you add the workflow:

1. Create an OPENAI_API_KEY repository or organization secret.
2. Save the workflow as .github/workflows/codex-security-review.yml.
3. Start with advisory comments. Tune the prompt and review the results before making the workflow a required check.

name: Codex Security pull request review

on:
  pull_request:
    types: [opened, synchronize, reopened]

jobs:
  security_review:
    if: github.event.pull_request.head.repo.full_name == github.repository
    runs-on: ubuntu-latest
    permissions:
      contents: read
    outputs:
      final_message: ${{ steps.run_codex.outputs.final-message }}

    steps:
      - uses: actions/checkout@v5
        with:
          ref: refs/pull/${{ github.event.pull_request.number }}/merge
          fetch-depth: 0
          persist-credentials: false

      - name: Fetch pull request refs
        env:
          PR_BASE_REF: ${{ github.event.pull_request.base.ref }}
          PR_NUMBER: ${{ github.event.pull_request.number }}
        run: |
          git fetch --no-tags origin \
            "$PR_BASE_REF" \
            "+refs/pull/$PR_NUMBER/head"

      - name: Run Codex Security review
        id: run_codex
        uses: openai/codex-action@v1
        with:
          openai-api-key: ${{ secrets.OPENAI_API_KEY }}
          sandbox: read-only
          output-file: codex-security-review.md
          prompt: |
            Review the pull request changes from
            ${{ github.event.pull_request.base.sha }} to
            ${{ github.event.pull_request.head.sha }} for security regressions.

            Focus on authentication, authorization, input handling, filesystem
            access, network requests, secrets, and changes to shared security
            controls. Return a concise Markdown review with affected paths and
            lines, evidence, impact, and remediation guidance. If there are no
            findings, summarize the security-sensitive surfaces reviewed and
            any coverage gaps.

      - name: Upload the review
        uses: actions/upload-artifact@v4
        with:
          name: codex-security-review
          path: codex-security-review.md

  post_review:
    needs: security_review
    if: needs.security_review.outputs.final_message != ''
    runs-on: ubuntu-latest
    permissions:
      issues: write
      pull-requests: write

    steps:
      - name: Post the review
        uses: actions/github-script@v7
        env:
          CODEX_FINAL_MESSAGE: ${{ needs.security_review.outputs.final_message }}
        with:
          github-token: ${{ github.token }}
          script: |
            await github.rest.issues.createComment({
              owner: context.repo.owner,
              repo: context.repo.repo,
              issue_number: context.payload.pull_request.number,
              body: process.env.CODEX_FINAL_MESSAGE,
            });

This workflow checks out the pull request merge commit and fetches the base and head refs so Codex can resolve the exact change. The security review job has read-only repository permissions. A separate job receives permission to post the final Markdown review, but it never receives the OpenAI API key.

For action inputs, privilege controls, and troubleshooting, see the Codex GitHub Action guide.