CVE-2025-27802

Medium

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. RTE properties (text fields), which could be used in the "Edit" section of the CMS, allowed the input of arbitrary text. It was possible to input malicious JavaScript code in these properties that would be executed if a user visits the previewed page. 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)

SeverityMedium
CVSS4.8
Exploit probability—
ProductEpiserver Content Management System (CMS)
PublishedJul 28, 2025
First seenJul 28, 2025

How to fix

Update
  • Optimizely Episerver Content Management System (CMS)11.21.4, 12.22.1 or later

Affected products

ProductAffected versionsFixed in
Optimizely Episerver Content Management System (CMS)11.x ≤ v < 11.21.4, 12.x ≤ v < 12.22.111.21.4, 12.22.1

Check your version

Choose the product and enter the version you run to see whether it falls in the affected range.

In the Intelligence 360 plan

Attack Surface Management

See the assets tied to your domains, the technologies they run and known vulnerabilities in one list.

CVE-2025-27802 · Episerver Content Management System (CMS) · Dark Radar