Umbraco CMS vulnerable to stored XSS via SVG File Upload

published 2023-12-12 2 y ago modified 2026-09-10 1 mo ago also GHSA-6xmx-85x3-4cv2 , EUVD-2023-3134

cvss: 3.7; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.4%; EPSS 0.4% chance of exploitation in 30 days, percentile 33%
public exploits: 0; none known

Umbraco is an ASP.NET content management system (CMS). Starting in version 7.0.0 and prior to versions 7.15.11, 8.18.9, 10.7.0, 11.5.0, and 12.2.0, a user with access to the backoffice can upload SVG files that include scripts. If the user can trick another user to load the media directly in a browser, the scripts can be executed. Versions 7.15.11, 8.18.9, 10.7.0, 11.5.0, and 12.2.0 contain a patch for this issue. Some workarounds are available. Implement the server side file validation or serve all media from an different host (e.g cdn) than where Umbraco is hosted.

Patch / fix

fixed in 2

nuget Umbraco.CMS 7.15.11, 8.18.9, 10.7.0, 11.5.0, 12.2.0
umbraco umbraco_cms 7.15.11, 8.18.9, 10.7.0, 11.5.0, 12.2.0

CISA SSVC

Exploitation: none
Automatable: no
Technical impact: partial
Assessed: 2 y ago (2024-08-28)

Exploit prediction

0.39% chance of exploitation in the next 30 days, higher than 33% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CNA	3.1	3.7	CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:L/I:L/A:N
NVD	3.1	5.4	CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
GitHub	3.1	0.0	CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:N/I:N/A:N

Affected packages

ecosystem	package	affected	fixed in
nuget	Umbraco.CMS	>=7.0.0, <7.15.11 >=8.0.0, <8.18.9 >=9.0.0, <10.7.0 >=11.0.0, <11.5.0 >=12.0.0, <12.2.0	7.15.11 8.18.9 10.7.0 11.5.0 12.2.0

Affected products

umbraco Umbraco-CMS

Classification

Weakness

CWE-79 Improper Neutralization of Input During Web Page Generation

References

github.com /umbraco/Umbraco-CMS/security/advisories/GHSA-6xmx-85x3-4cv2
web, vendor-advisory
docs.umbraco.com /umbraco-cms/reference/security/serverside-file-validation
web, product
nvd.nist.gov /vuln/detail/CVE-2023-49279
advisory
github.com /umbraco/Umbraco-CMS
package

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary