CVE-2025-27801

Stored Cross-Site Scripting in Episerver Content Management System (CMS) Media Selection Preview

Description

The Episerver Content Management System (CMS) by Optimizely was affected by multiple Stored Cross-Site Scripting (XSS) vulnerabilities. This allowed an authenticated attacker to execute malicious JavaScript code in the victim's browser. ContentReference properties, which could be used in the "Edit" section of the CMS, offered an upload functionality for documents. These documents could later be used as displayed content on the page. It was possible to upload SVG files that include malicious JavaScript code that would be executed if a user visited the direct URL of the preview image. Attackers needed at least the role "WebEditor" in order to exploit this issue. Affected products: Version 11.X: EPiServer.CMS.Core (<11.21.4) with EPiServer.CMS.UI (<11.37.5), Version 12.X: EPiServer.CMS.Core (<12.22.1) with EPiServer.CMS.UI (<11.37.3)

Remediation

Solution:

  • The vendor already provides a security patch (updated packages) which should be installed immediately.

Category

4.6
CVSS
Severity: Medium
CVSS 4.0 •
CVSS 3.1 •
EPSS 0.03%
Third-Party Advisory sec-consult.com
Affected: Optimizely Episerver Content Management System (CMS)
Published at:
Updated at:

References

Link Tags
https://api.nuget.optimizely.com/packages/episerver.cms.core/11.21.4# patch
https://api.nuget.optimizely.com/packages/episerver.cms.core/12.22.1# patch
https://r.sec-consult.com/optimizely third party advisory

Frequently Asked Questions

What is the severity of CVE-2025-27801?
CVE-2025-27801 has been scored as a medium severity vulnerability.
How to fix CVE-2025-27801?
To fix CVE-2025-27801: The vendor already provides a security patch (updated packages) which should be installed immediately.
Is CVE-2025-27801 being actively exploited in the wild?
As for now, there are no information to confirm that CVE-2025-27801 is being actively exploited. According to its EPSS score, there is a ~0% probability that this vulnerability will be exploited by malicious actors in the next 30 days.
What software or system is affected by CVE-2025-27801?
CVE-2025-27801 affects Optimizely Episerver Content Management System (CMS).
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