Pin GitHub Actions to full-length commit SHAs

[Dan Fiedler (danfiedler-msft)]

Summary

This PR pins GitHub Actions to full-length commit SHAs for improved security and reproducibility and adds a 7 day cooldown to Dependabot configuration for GitHub Actions. This work is described in more detail at https://aka.ms/action-pinning.

Why?

Pinning actions to commit SHAs prevents supply-chain attacks where a tag could be moved to point to malicious code. This is a recommended security best practice per the GitHub Actions security hardening guide.

This change mitigates the risk of tag retargeting to malicious code as seen in incidents like the tj-actions/changed-files action compromise or codfish/semantic-release-action compromise and improves the integrity and reproducibility of the CI/CD pipeline.

What changed?

Action pinning: Third-party action references in .github/workflows/ that used mutable tag-based references (e.g., actions/checkout@v4) have been updated to full-length commit SHAs with a version comment (e.g., actions/checkout@<sha> # v4) using the pinact tool. References that were already pinned to a SHA, or that used immutable release tags, were left unchanged.

Dependabot configuration: .github/dependabot.yml has been updated to ensure a github-actions package-ecosystem section is present with a cooldown configuration (default-days: 7). If the file did not exist, it was created. If a github-actions section already existed, only the cooldown block was added or its default-days value was increased to 7 if it was lower. The 7-day cooldown provides a window for the community to detect and report compromised releases before they are automatically proposed as updates, reducing exposure to supply-chain attacks via newly published malicious versions.

Is this safe to merge?

Yes. The pinned SHAs correspond to the same commits that the existing tags pointed to. No behavioral changes in action execution are introduced. You can verify the pinned SHA value using the GitHub REST API (e.g., the commit hash for actions/checkout@v7 can be found in the sha property in the JSON response for GET https://api.github.com/repos/actions/checkout/commits/v7).

Additional Information

For more information, please see https://aka.ms/action-pinning

[azure-pipelines]

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[github-actions]

Hello, and thank you for opening this pull request! 👋🏼 We appreciate the contribution.

We require pull request titles to follow the Conventional Commits specification and it looks like your proposed title needs to be adjusted.

Commits in this repo will typically be prefixed with fix:, feat:, docs:, chore:, refactor:, test:, or ci: to indicate the type of change being proposed. The linked specification has more details.

Details:

No release type found in pull request title "Pin GitHub Actions to full-length commit SHAs". Add a prefix to indicate what kind of release this pull request corresponds to. For reference, see https://www.conventionalcommits.org/

Available types:
 - feat: A new feature
 - fix: A bug fix
 - docs: Documentation only changes
 - style: Changes that do not affect the meaning of the code (white-space, formatting, missing semi-colons, etc)
 - refactor: A code change that neither fixes a bug nor adds a feature
 - perf: A code change that improves performance
 - test: Adding missing tests or correcting existing tests
 - build: Changes that affect the build system or external dependencies (example scopes: gulp, broccoli, npm)
 - ci: Changes to our CI configuration files and scripts (example scopes: Travis, Circle, BrowserStack, SauceLabs)
 - chore: Other changes that don't modify src or test files
 - revert: Reverts a previous commit

[Copilot]

Pull request overview

Hardens GitHub Actions references by pinning two reusable workflows to a full commit SHA.

Changes:

• Replaces 4.0 branch references with commit 5c9b2dea….
• Retains version comments for reference.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
.github/workflows/spec-review-stub.yml	Pins the spec-review workflow.
.github/workflows/check-rendered-specs-stub.yml	Pins the rendered-specs workflow.

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[reuben olinsky (reubeno)]

Dan Fiedler (@danfiedler-msft) Thanks for your contribution!

We're definitely fans of SHA-pinning github actions and had actually proactively enabled PR checks (via zizmor) to enforce that earlier this year. The notable exception are the actions in this repository that are referenced by this PR.

As the Copilot feedback on this PR calls out, this had been an intentional set-up so that the workflows in question will use the latest stable, already-merged versions of actions (from this repo) instead of anything changed as part of the PR itself.

We're open to some alternate approaches here but want to clarify that this had been intentional. Are there other approaches you'd recommend?