GHSA-c5g6-6xf7-qxp3 — @umbraco-cms/backoffice
MEDIUMGHSA-c5g6-6xf7-qxp3 is a medium-severity (CVSS 4.2) Cross-site Scripting (XSS) vulnerability in @umbraco-cms/backoffice. A fix is available for @umbraco-cms/backoffice — see the affected versions and patch details below.
Umbraco CMS vulnerable to stored Cross-site Scripting in the "dictionary name" on Dictionary section
Exploitation Status
No confirmed exploitation observed yet
- A successful exploit gives an attacker total control of the affected component, not partial access.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for GHSA-c5g6-6xf7-qxp3.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
GHSA-c5g6-6xf7-qxp3 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.
Where this sits among everything scored
Of 379,842 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.
Real-World Exposure
@umbraco-cms/backoffice.NETUmbraco.Cms.StaticAssetsReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects npm, NuGet packages — download data is not available via public APIs for these ecosystems.
Description
Umbraco, a free and open source .NET content management system, has a cross-site scripting vulnerability starting in version 14.0.0 and prior to versions 14.3.1 and 15.0.0. This can be leveraged to gain access to higher-privilege endpoints, e.g. if you get a user with admin privileges to run the code, you can potentially elevate all users and grant them admin privileges or access protected content. Versions 14.3.1 and 15.0.0 contain a patch. As a workaround, ensure that access to the Dictionary section is only granted to trusted users.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | @umbraco-cms/backoffice | ≥ 14.0.0&&< 14.3.1 | 14.3.1npm install @umbraco-cms/backoffice@14.3.1 |
| .NETNuGet | Umbraco.Cms.StaticAssets | ≥ 14.0.0&&< 14.3.1 | 14.3.1dotnet add package Umbraco.Cms.StaticAssets --version 14.3.1 |
Affected Products
umbraco cmsumbracoDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for @umbraco-cms/backoffice, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update @umbraco-cms/backoffice to 14.3.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-c5g6-6xf7-qxp3 is resolved across your whole dependency graph.
Workarounds
Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page.
Frequently Asked Questions
Is GHSA-c5g6-6xf7-qxp3 in your dependencies?
Find it across npm, NuGet, including transitive dependencies.