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Security Guide

A hook configuration is executable project code. Installing a Git shim or running prek run authorizes the selected hooks, their installation steps, and their dependencies to execute with the current user's permissions.

Review configurations before running them

Treat an unfamiliar prek.toml or .pre-commit-config.yaml like an unfamiliar build script:

  • Review remote repository URLs, revisions, hook entries, and additional dependencies.
  • Review local hooks and checked-in scripts, especially entries that explicitly invoke a shell.
  • Inspect configuration changes in pull requests before running them locally.
  • Use tighter credentials and isolation for untrusted repositories.

This is especially important for a global Git hook that discovers and runs each repository's config automatically. Such a hook can execute project-controlled code during an ordinary Git operation.

Pin remote hooks

A full commit SHA is the strongest Git pin because it names immutable content. A version tag is easier to read and is commonly used for releases, but Git tags can be moved by a repository maintainer. Branch names are mutable and should not be treated as repeatable pins.

Use prek update --freeze to write commit SHAs when immutable pins are required. Review the resulting revision changes before committing them.

Downloads and checksums

For managed download paths that support checksum sidecars, prek verifies the download when the upstream source provides that metadata. The download checksum policy controls what happens when metadata is missing; it cannot create authenticity information that an upstream source did not publish.

Release artifacts for prek itself include GitHub attestations. See Artifact Verification.

Credentials and logs

Use a credential helper or short-lived CI token for private hook repositories. Avoid embedding credentials in repository URLs or configuration files. Verbose hook output and prek.log can contain repository paths, command arguments, and tool output, so review and redact logs before sharing them publicly.