# CVE-2026-55067: Vikunja: Authenticated cross-tenant kanban-bucket relocation via `project_view_id` mass-assignment

> Authenticated users can move buckets to other tenants' views via mass assignment, enabling cross-tenant defacement in Vikunja.

- **Severity:** Medium 5.0 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:L/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 28 Aug 2026
- **Updated:** 28 Aug 2026
- **Also known as:** GHSA-569v-q83c-3j3g, GO-2026-6307

## What is CVE-2026-55067?

CVE-2026-55067 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. Prior to 2.4.0, POST /api/v1/projects/{project}/views/{view}/buckets/{bucket} allows the request body project_view_id value to be mass assigned by Bucket.Update in pkg/models/kanban.go. The permission check validates that the bucket currently belongs to the URL project and view but does not validate the body selected destination view, allowing any authenticated user to relocate an attacker-owned bucket into another tenant’s Kanban view. The injected bucket retains attacker-controlled content and ownership, enabling cross-tenant defacement. This issue is fixed in version 2.4.0.

Weakness: CWE-639 (Authorization Bypass Through User-Controlled Key)

## Which versions are affected by CVE-2026-55067?

3 open source packages ship an affected version, including code.vikunja.io/api.


| Package | Ecosystem | 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-2026-55067?

Upgrade code.vikunja.io/api to 2.4.0 or later.

## Is CVE-2026-55067 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-55067 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-55067 and fix it if it is affected.

What it is: CVE-2026-55067 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.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-55067 exists.

Affected packages and fixed versions:
- code.vikunja.io/api (Go): affected all versions; no fix listed
- code.vikunja.io/api (Go): affected all versions; fixed in 2.4.0
- code.vikunja.io/api (Go): affected all versions; fixed in 2.4.0

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-55067/ (Markdown: https://insights.sbomify.com/CVE-2026-55067/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-55067
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-55067
- OSV: https://osv.dev/vulnerability/CVE-2026-55067

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-55067/
Summaries are generated and may contain mistakes; the official description above is the record.