CVE-2026-55064: go-vikunja vikunja Missing Authorization

Vulnerability summary

CVE-2026-55064 is a medium (CVSS 4.3) Missing Authorization vulnerability in go-vikunja vikunja. EPSS estimates a 0.37% chance of exploitation in the next 30 days, higher than 29.1% of scored vulnerabilities.

Timeline

1. 28-08-2026
   PublishedVulnerability first disclosed.
2. 28-08-2026
   Last modifiedVulnerability information updated.

Description

Vikunja is an open-source self-hosted task management platform. From 2.3.0 until 2.4.0, a user with Write but not Admin permission on a shared child project can detach it from its parent hierarchy by submitting parent_project_id equal to 0 to POST /api/v1/projects/{project}. The Project.CanUpdate authorization check in pkg/models/project_permissions.go and UpdateProject logic in pkg/models/project.go only gate nonzero parent values, while UpdateProject always persists parent_project_id, so the explicit zero value bypasses the Admin requirement introduced for CVE-2026-35595. Detachment severs the recursive permission-inheritance chain and can disrupt the owner’s hierarchy and inherited collaborator access. This issue is fixed in version 2.4.0.

• CWE-862Missing AuthorizationThe product does not perform an authorization check when an actor attempts to access a resource or perform an action.