XSS in Optimizely Episerver Content Management System (Cms)
CVE-2025-27800
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)
Vulnerability class: XSS (Cross-Site Scripting)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 4.8 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:N.
EPSS exploit prediction
EPSS: 0.004 (28.8th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 29th percentile — 28.8% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.004 · newest: 0.004 · change: +0.000
Affected products
- Optimizely Episerver Content Management System (Cms) — versions 11.x, 12.x
Weakness classification (CWE)
References
- 551230f0-3615-47bd-b7cc-93e92e730bbf (patch)
- 551230f0-3615-47bd-b7cc-93e92e730bbf (patch)
- 551230f0-3615-47bd-b7cc-93e92e730bbf (third-party-advisory)
- af854a3a-2127-422b-91ae-364da2661108
Frequently asked questions
- What is CVE-2025-27800?
- CVE-2025-27800 is a medium-severity vulnerability in Optimizely Episerver Content Management System (Cms), classified under Cross-site Scripting. CVSS score: 4.8/10. Published 2025-07-28.
- How severe is CVE-2025-27800?
- Medium severity. CVSS v3 base score is 4.8 out of 10.