NIST deprecates RSA-2048 from 2030. Find every one of them before attackers do.
.NET
.NET NuGet
Not in CISA KEV
MEDIUM severity

CVE-2024-35218 — UmbracoCms.Core

MEDIUMFix: umbraco/Umbraco-CMS@1b712fe

CVE-2024-35218 is a medium-severity (CVSS 4.2) Cross-site Scripting (XSS) vulnerability in UmbracoCms.Core. A fix is available for UmbracoCms.Core — see the affected versions and patch details below.

Umbraco CMS Vulnerable to Stored XSS on Content Page Through Markdown Editor Preview Pane

Also known asGHSA-gvpc-3pj6-4m9w
Published
Updated
Affected
4 pkgs
Patched
4 / 4
Exploits
None indexed
Exploitation data as of Nov 10, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

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 CVE-2024-35218.

EPSS Exploitation Probability

via FIRST.org ↗
0.4%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs29th percentile — riskier than 29% of all scored CVEsHighest risk
0.00%0.40%0.80%1.21%0.7%0.4%May 26Sep 26Nov 26

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

4 pkgs affected
.NETUmbracoCms.Core.NETUmbracoCms.Core.NETUmbracoCms.Core.NETUmbracoCms.Core

Real-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

Umbraco CMS is an ASP.NET CMS used by more than 730.000 websites. Stored Cross-site scripting (XSS) enable attackers that have access to backoffice to bring malicious content into a website or application. This vulnerability has been patched in version(s) 8.18.13, 10.8.4, 12.3.7, 13.1.1 by implementing IHtmlSanitizer.

Affected Packages

4 total 4 fixed
EcosystemPackageVulnerable rangeFix
.NETNuGetUmbracoCms.Core≥ 8.0.0&&< 8.18.138.18.13dotnet add package UmbracoCms.Core --version 8.18.13
.NETNuGetUmbracoCms.Core≥ 10.0.0&&< 10.8.410.8.4dotnet add package UmbracoCms.Core --version 10.8.4
.NETNuGetUmbracoCms.Core≥ 12.0.0&&< 12.3.712.3.7dotnet add package UmbracoCms.Core --version 12.3.7
.NETNuGetUmbracoCms.Core≥ 13.0.0&&< 13.1.113.1.1dotnet add package UmbracoCms.Core --version 13.1.1

Affected Products

1 product · 4 configurations
Application
umbraco cmsumbraco
≥ 13.0.0 && < 13.1.1
range

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for UmbracoCms.Core, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update UmbracoCms.Core to 8.18.13 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2024-35218 is resolved across your whole dependency graph.

  3. 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

Umbraco CMS is an ASP.NET CMS used by more than 730.000 websites. Stored Cross-site scripting (XSS) enable attackers that have access to backoffice to bring malicious content into a website or application. This vulnerability has been patched in version(s) 8.18.13, 10.8.4, 12.3.7, 13.1.1 by implementing IHtmlSanitizer.
O3 Security · Impact-Aware SCA

Is CVE-2024-35218 in your dependencies?

Find it across NuGet, including transitive dependencies.

Scan my dependencies How O3 SCA works
CVE-2024-35218: UmbracoCms XSS — Fixed in 8.18.13