CVE-2026-55064 Vikunja has an incomplete fix for CVE-2026-35595: Write-only user can detach shared project from parent hierarchy via parent_project_id=0
A write-only user can detach a shared project from its parent hierarchy, bypassing admin checks and disrupting permission inheritance.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-55064?
CVE-2026-55064 is a medium-severity missing authorization vulnerability in go-vikunja vikunja, published on 28 Aug 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official 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.
Weakness: CWE-862
Which versions are affected by CVE-2026-55064?
3 open source packages ship an affected version, including code.vikunja.io/api.
| Package | Affected | Fixed in |
|---|---|---|
code.vikunja.io/api Go | All versions | None |
code.vikunja.io/api Go | From 2.3.0 | 2.4.0 |
code.vikunja.io/api Go | From 2.3.0 | 2.4.0 |
How do I fix CVE-2026-55064?
Upgrade code.vikunja.io/api to 2.4.0 or later.
Upgrade, and check permissions on every request on the server, not only in the interface. More about Missing authorization.
Is CVE-2026-55064 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-55064 exists.
Sources
Also known as GHSA-44v6-7fxq-vgf4, GO-2026-6306.