CVE-2025-27800 Stored Cross-Site Scripting in Episerver Content Management System (CMS) Admin Dashboard
Authenticated attackers can inject malicious JavaScript into CMS admin dashboard notes, leading to code execution in victims' browsers.
- Exploited in the wild
- Not known
- Login needed
- An administrator
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- None listed
What is CVE-2025-27800?
CVE-2025-27800 is a medium-severity cross-site scripting vulnerability in Optimizely Episerver Content Management System (CMS), published on 28 Jul 2025. An attacker needs administrator access to exploit it, and only if a user opens a file or follows a link.
Official 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.
The Admin dashboard offered the functionality to add gadgets to the dashboard. This included the "Notes" gadget. An authenticated attacker with the corresponding access rights (such as "WebAdmin") that was impersonating the victim could insert malicious JavaScript code in these notes that would be executed if the victim visited the dashboard.
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)
Weakness: CWE-79
Which versions are affected by CVE-2025-27800?
How do I fix CVE-2025-27800?
No fix has been published for CVE-2025-27800 yet. Limit exposure of the affected software until one is available.
Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.
Is CVE-2025-27800 being exploited?
There is no known exploitation of CVE-2025-27800 in the wild and no public exploit code.
Sources
Also known as GHSA-9p6h-f8wj-744p.