CVE-2026-55066 Vikunja: Cross-tenant IDOR in kanban move-task endpoint via unauthorized body task_id
Authenticated users can read and modify other tenants' tasks by manipulating task IDs in kanban move requests due to missing authorization checks.
- 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-2026-55066?
CVE-2026-55066 is a high-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. Prior to 2.4.0, POST /api/v1/projects/{project}/views/{view}/buckets/{bucket}/tasks accepts a body supplied task_id but TaskBucket.CanUpdate in pkg/models/kanban_task_bucket.go authorizes only the project, view, and bucket from the URL. updateTaskBucket then calls Task.ReadOne without a separate task permission check, returns the victim task contents, and can update the task done state when the attacker chooses a done bucket. Because task identifiers are global sequential values, an authenticated user can enumerate cross-tenant tasks and modify their completion metadata through both the v1 and v2 routes that share this model. This issue is fixed in version 2.4.0.
Weakness: CWE-639
Which versions are affected by CVE-2026-55066?
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 | All versions | 2.4.0 |
code.vikunja.io/api Go | All versions | 2.4.0 |
How do I fix CVE-2026-55066?
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-2026-55066 being exploited?
There is no known exploitation of CVE-2026-55066 in the wild and no public exploit code.
Sources
Also known as GHSA-5pg6-m483-7vrg, GO-2026-6308.