Affected: go-vikunja vikunja

Vikunja from 1.0.0-rc0 before 2.7.0 contains an improper authorization vulnerability in RecalculateTaskPositions that allows authenticated users with zero accessible projects to write task_positions rows for all tasks instance-wide. Attackers can delete their Inbox after repointing default_project_id, then create empty-filter saved filters to persist cross-tenant references and amplify writes for denial of service.