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.NET
.NET NuGet
Not in CISA KEV
LOW severity

CVE-2024-35239 — Umbraco.Forms

LOW

CVE-2024-35239 is a low-severity (CVSS 2.7) Cross-site Scripting (XSS) vulnerability in Umbraco.Forms. A fix is available for Umbraco.Forms — see the affected versions and patch details below.

Umbraco Forms components vulnerable to Stored Cross-site Scripting

Published
Updated
Affected
4 pkgs
Patched
4 / 4
Exploits
None indexed
Exploitation data as of Nov 4, 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-2024-35239.

EPSS Exploitation Probability

via FIRST.org ↗
0.3%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs28th percentile — riskier than 28% of all scored CVEsHighest risk
0.00%0.36%0.71%1.07%0.6%0.3%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
.NETUmbraco.Forms.NETUmbraco.Forms.NETUmbraco.Forms.NETUmbraco.Forms

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

Impact

Authenticated user that has access to edit Forms may inject unsafe code into Forms components.

Patches

Issue can be mitigated by configuring TitleAndDescription:AllowUnsafeHtmlRendering after upgrading to patched versions (13.0.1, 12.2.2, 10.5.3, 8.13.13).

References

https://docs.umbraco.com/umbraco-forms/release-notes#id-13.0.1-january-16th-2024 https://docs.umbraco.com/umbraco-forms/v/12.forms.latest/release-notes#id-12.2.2-january-16th-2024 https://docs.umbraco.com/umbraco-forms/v/10.forms.latest/release-notes https://docs.umbraco.com/umbraco-forms/developer/configuration#editing-configuration-values

Affected Packages

4 total 4 fixed
EcosystemPackageVulnerable rangeFix
.NETNuGetUmbraco.Forms≥ 13.0.0&&< 13.0.113.0.1dotnet add package Umbraco.Forms --version 13.0.1
.NETNuGetUmbraco.Forms≥ 12.0.0&&< 12.2.212.2.2dotnet add package Umbraco.Forms --version 12.2.2
.NETNuGetUmbraco.Forms≥ 10.0.0&&< 10.5.310.5.3dotnet add package Umbraco.Forms --version 10.5.3
.NETNuGetUmbraco.Forms≥ 8.0.0&&< 8.13.138.13.13dotnet add package Umbraco.Forms --version 8.13.13

Affected Products

1 product · 4 configurations
Application
umbraco formsumbraco
≥ 13.0.0 && < 13.0.1
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 Umbraco.Forms, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update Umbraco.Forms to 13.0.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2024-35239 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

### Impact Authenticated user that has access to edit Forms may inject unsafe code into Forms components. ### Patches Issue can be mitigated by configuring TitleAndDescription:AllowUnsafeHtmlRendering after upgrading to patched versions (13.0.1, 12.2.2, 10.5.3, 8.13.13). ### References https://docs.umbraco.com/umbraco-forms/release-notes#id-13.0.1-january-16th-2024 https://docs.umbraco.com/umbraco-forms/v/12.forms.latest/release-notes#id-12.2.2-january-16th-2024 https://docs.umbraco.com/umbraco-forms/v/10.forms.latest/release-notes https://docs.umbraco.com/umbraco-forms/developer/configurat
O3 Security · Impact-Aware SCA

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CVE-2024-35239: Umbraco.Forms — Fixed in 13.0.1