Vikunja: Unauthenticated Instance-Wide Data Breach via Link Share Hash Disclosure Chained with Cross-Project Attachment IDOR

Summary Two independently-exploitable authorization flaws in Vikunja can be chained to allow an unauthenticated attacker to download and delete every file attachment across all projects in a Vikunja instance. The ReadAll endpoint for link shares exposes share hashes including admin-level shares t...