Umbraco CMS Vulnerable to Stored XSS on Content Page Through Markdown Editor Preview Pane
Priority LOW 22CWE-79Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- High
- User interaction
- Required
- Attack complexity
- Low
- Impact type
- Cross-site scripting
- Confidentiality · integrity · availability
- Low · Low · None
- Fix status
- Fixed
Attack profile from CVSS 3.1 · NVD. Fix status from CNA and GitHub. Impact type from CWE-79.
Summary
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.
Why it matters now
Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00354 29th percentileScored 2026-11-07
Fix Fixed Umbraco-CMS (umbraco): 8.18.13, 10.8.4, 12.3.7 +1UmbracoCms.Core (NuGet): 8.18.13, 10.8.4, 12.3.7 +1
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| umbraco | Umbraco-CMS | 8.0.0 to before 8.18.13; 10.0.0 to before 10.8.4; 12.0.0 to before 12.3.7; 13.0.0 to before 13.1.1 | 8.18.13, 10.8.4, 12.3.7, 13.1.1 | Patch available | CNA |
| — | UmbracoCms.Core (NuGet) | 8.0.0 to before 8.18.13 | 8.18.13 | Patch available | GHSA-gvpc-3pj6-4m9w |
| — | UmbracoCms.Core (NuGet) | 10.0.0 to before 10.8.4 | 10.8.4 | Patch available | GHSA-gvpc-3pj6-4m9w |
| — | UmbracoCms.Core (NuGet) | 12.0.0 to before 12.3.7 | 12.3.7 | Patch available | GHSA-gvpc-3pj6-4m9w |
| — | UmbracoCms.Core (NuGet) | 13.0.0 to before 13.1.1 | 13.1.1 | Patch available | GHSA-gvpc-3pj6-4m9w |
- Umbraco-CMS Vendorumbraco Affected 8.0.0 to before 8.18.13; 10.0.0 to before 10.8.4; 12.0.0 to before 12.3.7; 13.0.0 to before 13.1.1 Fixed in 8.18.13, 10.8.4, 12.3.7, 13.1.1 Patch available CNA
- UmbracoCms.Core (NuGet) Vendor— Affected 8.0.0 to before 8.18.13 Fixed in 8.18.13 Patch available GHSA-gvpc-3pj6-4m9w
- UmbracoCms.Core (NuGet) Vendor— Affected 10.0.0 to before 10.8.4 Fixed in 10.8.4 Patch available GHSA-gvpc-3pj6-4m9w
- UmbracoCms.Core (NuGet) Vendor— Affected 12.0.0 to before 12.3.7 Fixed in 12.3.7 Patch available GHSA-gvpc-3pj6-4m9w
- UmbracoCms.Core (NuGet) Vendor— Affected 13.0.0 to before 13.1.1 Fixed in 13.1.1 Patch available GHSA-gvpc-3pj6-4m9w
CPE configurations NVD · 1
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:umbraco:umbraco_cms:*:*:*:*:*:*:*:* | 8.0.0 to before 8.18.13; 10.0.0 to before 10.8.4; 12.0.0 to before 12.3.7; 13.0.0 to before 13.1.1 | Vulnerable | umbraco |
- cpe:2.3:a:umbraco:umbraco_cms:*:*:*:*:*:*:*:* Versions 8.0.0 to before 8.18.13; 10.0.0 to before 10.8.4; 12.0.0 to before 12.3.7; 13.0.0 to before 13.1.1 Vulnerable ·umbraco
Remediation
- Fix · CNA Umbraco-CMS (umbraco) Fixed in 8.18.13, 10.8.4, 12.3.7, 13.1.1
- Fix · GHSA-gvpc-3pj6-4m9w UmbracoCms.Core (NuGet) Fixed in 8.18.13 Advisory →
- Fix · GHSA-gvpc-3pj6-4m9w UmbracoCms.Core (NuGet) Fixed in 10.8.4 Advisory →
- Fix · GHSA-gvpc-3pj6-4m9w UmbracoCms.Core (NuGet) Fixed in 12.3.7 Advisory →
- Fix · GHSA-gvpc-3pj6-4m9w UmbracoCms.Core (NuGet) Fixed in 13.1.1 Advisory →
Timeline
- 2026-10-02 Threatist record created from CVE-2024-35218
- 2026-10-03 Alias added: GHSA-gvpc-3pj6-4m9w
References
Patch 4
- 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
Advisory 2
More Umbraco Cms vulnerabilities
- TI-2025-41183 An arbitrary file upload vulnerability in Umbraco CMS v16.3.3 allows attackers to execute… CVSS 3.1CRITICAL 10.0
- TI-2012-05477 Umbraco CMS < 4.7.1 codeEditorSave.asmx RCE CVSS 4.0CRITICAL 9.3
- TI-2021-22392 Umbraco v8.14.1 - 'baseUrl' SSRF CVSS 4.0MEDIUM 6.9
- TI-2024-36846 A stored cross-site scripting (XSS) vulnerability in Umbraco CMS v14.3.1 allows attackers… CVSS 3.1MEDIUM 6.5
- TI-2019-15240 Umbraco CMS 4.11.8 through 7.15.10, and 7.12.4, allows Remote Code Execution by… CVSS 3.1HIGH 7.2
- TI-2020-04738 Cross-site scripting in Umbraco CMS CVSS 3.1MEDIUM 5.4
Sources
- CVE-2024-35218 · CVE Program
- CVE-2024-35218 · NVD
- FIRST EPSS
- GHSA-gvpc-3pj6-4m9w · GitHub Advisory Database · CC BY 4.0
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