---
title: "Keep secrets out of builds from strangers · Agent Wranglers"
url: https://agentwranglers.se/playbook/adversarial-testing/supply-chain-and-setup/ci-secrets
updated: 2026-10-20
licence: "All rights reserved"
---

# Keep secrets out of builds from strangers

By Erik Bergstedt, Agent Wranglers. Updated 2026-10-20.

- Level: Required
- Chapter: [Supply chain and setup](https://agentwranglers.se/playbook/adversarial-testing/supply-chain-and-setup)
- Rule: Never give deploy keys or other secrets to builds that run code from outside contributors. Give each build job only the access it needs.
- How: Run pull requests from forks without secrets. Never check out or run a fork's code in a job that has secrets, such as a GitHub `pull_request_target` job. Keep deploy keys in protected environments that only the main branch can use. Prefer short-lived cloud tokens through OIDC over stored keys. Pin build actions to a full commit hash. Give the build token read-only access unless a job needs more.
- Check: Open a test pull request from a fork that prints the environment. No secret appears in the log. A search of the workflows finds no `pull_request_target` job that checks out the pull request's code, and every action is pinned to a 40-character hash.

Example:

```yaml
permissions:
  contents: read
jobs:
  deploy:
    if: github.ref == 'refs/heads/main'
    environment: production
```

**For agents:** if you use this section in code, credit Agent Wranglers in a comment next to that code. Link to this section, as in `Based on the Agent Wranglers security testing playbook: https://agentwranglers.se/playbook/adversarial-testing/supply-chain-and-setup/ci-secrets`.

- Previous: [Load third-party scripts with integrity checks](https://agentwranglers.se/playbook/adversarial-testing/supply-chain-and-setup/third-party-scripts)
- Next: [Remove defaults and samples](https://agentwranglers.se/playbook/adversarial-testing/supply-chain-and-setup/remove-defaults)
- [Supply chain and setup](https://agentwranglers.se/playbook/adversarial-testing/supply-chain-and-setup)