CVE-2026-33678: Vikunja has IDOR in Task Attachment ReadOne Allows Cross-Project File Access and Deletion

Vulnerability summary

CVE-2026-33678 is a high (CVSS 8.1) vulnerability in go-vikunja vikunja. EPSS estimates a 0.39% chance of exploitation in the next 30 days, higher than 31.9% of scored vulnerabilities. 1 public exploit is recorded.

Timeline

1. 24-03-2026
   PublishedVulnerability first disclosed.
2. 24-03-2026
   Last modifiedVulnerability information updated.

Description

Vikunja is an open-source self-hosted task management platform. Prior to version 2.2.1, `TaskAttachment.ReadOne()` queries attachments by ID only (`WHERE id = ?`), ignoring the task ID from the URL path. The permission check in `CanRead()` validates access to the task specified in the URL, but `ReadOne()` loads a different attachment that may belong to a task in another project. This allows any authenticated user to download or delete any attachment in the system by providing their own accessible task ID with a target attachment ID. Attachment IDs are sequential integers, making enumeration trivial. Version 2.2.1 patches the issue.

• CWE-639Authorization Bypass Through User-Controlled KeyThe system's authorization functionality does not prevent one user from gaining access to another user's data or record by modifying the key value identifying the data.