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

MEDIUM
4.3
CVSS Score
Published: August 28, 2026 at 04:38 PM UTC
Updated: September 9, 2026 at 09:27 PM UTC
1 product affected across 1 vendorVikunja

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Severity
MEDIUM4.3
Exploit prediction
EPSS 0.4%
SSVC
PoC

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v < 2.4.0
Affected range stops below 2.4.0, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet, and no fixed version or vendor advisory is recorded against it.

SSVC — Action Prioritization

SSVCPoCNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

4.3MEDIUMGitHub_M
Attack Vector
NETWORK
Complexity
LOW
Privileges
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
LOW
Availability
NONE
Vector?

Quick Info

StatusDEFERRED
CWE
CWE-862

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