Summary
Stored XSS via SVG File Upload
Workaround
Implement the server side file validation
https://docs.umbraco.com/umbraco-cms/reference/security/serverside-file-validation
or
Serve all media from an different host (e.g cdn) that where umbraco is hosted
Impact
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.
Untrusted input is rendered as active markup in a victim's browser, which can run script in their session. Typical impact: session or credential theft, and actions taken as the user.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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See it in your environmentNew to Kodem? Get a demo →Remediation advice
Umbraco.CMS to 7.15.11 or later; Umbraco.CMS to 8.18.9 or later; Umbraco.CMS to 10.7.0 or later; Umbraco.CMS to 11.5.0 or later; Umbraco.CMS to 12.2.0 or later
Kodem Kai can prioritize this vulnerability in your dependency tree and generate a fix recommendation.
Frequently Asked Questions
- What is CVE-2023-49279? CVE-2023-49279 is a low-severity cross-site scripting (XSS) vulnerability in Umbraco.CMS (nuget), affecting versions >= 7.0.0, < 7.15.11. It is fixed in 7.15.11, 8.18.9, 10.7.0, 11.5.0, 12.2.0. Untrusted input is rendered as active markup in a victim's browser, which can run script in their session.
- Which versions of Umbraco.CMS are affected by CVE-2023-49279? Umbraco.CMS (nuget) versions >= 7.0.0, < 7.15.11 is affected.
- Is there a fix for CVE-2023-49279? Yes. CVE-2023-49279 is fixed in 7.15.11, 8.18.9, 10.7.0, 11.5.0, 12.2.0. Upgrade to this version or later.
- Is CVE-2023-49279 exploitable, and should I be worried? Whether CVE-2023-49279 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2023-49279 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2023-49279?
- Upgrade
Umbraco.CMSto 7.15.11 or later - Upgrade
Umbraco.CMSto 8.18.9 or later - Upgrade
Umbraco.CMSto 10.7.0 or later - Upgrade
Umbraco.CMSto 11.5.0 or later - Upgrade
Umbraco.CMSto 12.2.0 or later
- Upgrade