Executive brief
Vikunja, an open-source collaboration and task management platform, contains security flaws that allow unauthorized users to access and delete files across an entire organization. By using a single publicly shared link, an attacker can escalate their permissions to gain administrative control over project shares. This allows them to download or permanently delete every file attachment from every project on the server, leading to significant data theft and operational disruption.
Technical details
Vikunja contains two critical authorization flaws. First, the 'LinkSharing.ReadAll' endpoint fails to redact share hashes when returning project shares to users with read-only access, allowing an attacker to obtain admin-level share hashes and escalate privileges. Second, the 'GetTaskAttachment' endpoint (ReadOne) suffers from an Insecure Direct Object Reference (IDOR) vulnerability; while it validates permissions against a provided task ID, it retrieves the actual attachment using a sequential ID without verifying that the attachment belongs to the authorized task. By chaining these, a remote attacker with access to a single public link share can enumerate, download, and delete all file attachments across all projects on the instance. The vulnerabilities are patched in version 2.2.1.
Affected products
- Vikunja Vikunja < 2.2.1
Timeline
- 2026-03-23: advisory: Initial GHSA advisory published
- 2026-07-10: disclosed: NVD publication date