GHSA-v98m-398x-269r — Umbraco.CMS
MEDIUMGHSA-v98m-398x-269r is a medium-severity (CVSS 4.3) Cross-site Scripting (XSS) vulnerability in Umbraco.CMS. A fix is available for Umbraco.CMS — see the affected versions and patch details below.
DOM-XSS on Backoffice login screen.
Exploitation Status
No confirmed exploitation observed yet
- 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-v98m-398x-269r.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
GHSA-v98m-398x-269r plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 377,166 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
Umbraco.CMS.NETUmbraco.CMSReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects NuGet packages — download data is not available via public APIs for these ecosystems.
Description
Impact
Cross-site scripting (XSS) enable attackers to bring malicious content into a website or application.
Explanation of the vulnerability
A DOM-XSS can be exploited when users are successfully logging into the Backoffice.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| .NETNuGet | Umbraco.CMS | ≥ 10.0.0&&< 10.8.1 | 10.8.1dotnet add package Umbraco.CMS --version 10.8.1 |
| .NETNuGet | Umbraco.CMS | ≥ 11.0.0&&< 12.3.4 | 12.3.4dotnet add package Umbraco.CMS --version 12.3.4 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for Umbraco.CMS, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update Umbraco.CMS to 10.8.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-v98m-398x-269r 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 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like GHSA-v98m-398x-269r can be triaged on real exposure rather than presence alone.
Tailored to GHSA-v98m-398x-269r. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-v98m-398x-269r in your dependencies?
O3 Security finds GHSA-v98m-398x-269r across NuGet dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.