Kurrier: Authenticated cross-user authorization bypass in Kurrier API

Summary

Kurrier is a modern, self-hosted workspace for email, calendar, contacts, and storage. Prior to 1.2.4, Kurrier API endpoints for listing and retrieving webhook and identity resources did not enforce ownership checks for authenticated API requests. An attacker with a valid API key could use another account's identifiers to read and enumerate webhook and identity resources belonging to that account through apps/worker/server/routes/api/kurrier/webhooks/[id].get.ts, apps/worker/server/routes/api/kurrier/webhooks/index.get.ts, apps/worker/server/routes/api/kurrier/identities/[id].get.ts, and apps/worker/server/routes/api/kurrier/identities/index.get.ts. Anonymous requests and invalid API keys were rejected, and cross-user modification operations were blocked, but affected GET and list operations could expose another user's resource metadata. This issue is fixed in version 1.2.4.