CVE-2026-27638 ActualBudget missing authorization in sync endpoints allows cross-user budget file access in multi-user mode

Actual is a local-first personal finance tool. Prior to version 26.2.1, in multi-user mode OpenID, the sync API endpoints /sync/ don't verify that the authenticated user owns or has access to the file being operated on. Any authenticated user can read, modify, and overwrite any other user's budge...