CVE-2026-56765: Vikunja - Unauthenticated Instance-Wide Data Breach via Link Share Hash Disclosure Chained with Cross-Project Attachment IDOR
Vikunja before 2.2.1 contains an authorization flaw where the LinkSharing.ReadAll endpoint exposes share hashes to users with read access, enabling permission escalation to admin-level shares. The GetTaskAttachment endpoint performs permission checks against user-supplied task IDs but fetches attachments by sequential ID without verifying ownership, allowing attackers to download and delete all file attachments across all projects instance-wide.
Affected Software
Event History
Frequently Asked Questions
What is the severity of CVE-2026-56765?
The severity of CVE-2026-56765 is critical, rated at 9.3.
How do I fix CVE-2026-56765?
To fix CVE-2026-56765, upgrade Vikunja to version 2.2.1 or later.
What type of vulnerability is CVE-2026-56765?
CVE-2026-56765 is an authorization flaw that allows unauthenticated access to sensitive data.
What can attackers do with CVE-2026-56765?
Attackers can exploit CVE-2026-56765 to escalate permissions and access admin-level shares.
Which software is affected by CVE-2026-56765?
CVE-2026-56765 affects Vikunja versions prior to 2.2.1.