CVE-2026-55064 is a medium-severity (CVSS 4.3) CWE-862 vulnerability in code.vikunja.io/api. O3 Security confirms whether CVE-2026-55064 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Vikunja incomplete fix for CVE-2026-35595: Write-only user can detach shared project from parent hierarchy via parent_project_id=0
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-55064.
Real-World Exposure
code.vikunja.io/apiReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.
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 Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | code.vikunja.io/api | ≥ 2.3.0&&< 2.4.0 | 2.4.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for code.vikunja.io/api. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update code.vikunja.io/api to 2.4.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-55064 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether CVE-2026-55064 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to CVE-2026-55064. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-55064 in your dependencies?
O3 detects CVE-2026-55064 across Go dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.