WeKan Board Export REST Endpoints: NULL Pointer Dereference on Invalid authToken Leads to Uncaught Exception / Remote Denial of Service

Wekan is open source kanban built with Meteor. Prior to 10.38, the /api/boards/:boardId/export, /api/boards/:boardId/attachments/:attachmentId/export, /api/boards/:boardId/export/csv, and /api/boards/:boardId/exportExcel handlers in models/export.js and models/exportExcel.js looked up a user from the attacker-controlled authToken query parameter and immediately called user._id.toString() without checking whether ReactiveCache.getUser() returned undefined. A request for a private board with an unknown token therefore threw a TypeError from an asynchronous route, producing an unhandled rejection that could terminate the Wekan process and deny service to all users. Version 10.38 adds a 401 guard after every export token lookup and wraps export handlers with safeRoute() so unexpected exceptions become controlled responses. This issue is fixed in version 10.38.