Taiga taiga-back Private Project Member Roster Disclosure via Unauthenticated filters_data Endpoints

Taiga 6.10.1 contains a missing authorization vulnerability that allows unauthenticated attackers to disclose the full member roster and internal workflow configuration of any private project by supplying a project ID to the filters_data API endpoints on UserStory, Task, Issue, and Epic viewsets. Attackers can send unauthenticated GET requests to the filters_data endpoints with sequential integer project IDs to enumerate private project membership details including user IDs, full names, and gravatar hashes, bypassing the access controls that correctly restrict other project API endpoints.