CVE-2025-27801: The Episerver Content Management System (CMS) by Optimizely was affected by multiple Stored
Source GCVE Database
Not known to be exploited · CVSS 4.6 Medium · fixed in 13.0.0 : update Episerver Content Management System (CMS) when convenient.
Data as of 29 Oct 2026, 22:52 UTC
Thin evidence
One scorer or none| CNA (SEC-VLab) | CVSS 4.0 | 4.6 |
|---|---|---|
| CNA (SEC-VLab) | CVSS 3.1 | 4.8 |
- Patch
- Available – fixed in 13.0.0, 12.22.1, 12.0.0 +3
CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:A/VC:N/VI:L/VA:L/SC:L/SI:L/SA:NExploitation evidence
Disclosed: evidence found.
CVE published 28 Jul 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 29 Oct 2026.
What to do
Upgrade episerver.cms.core to 13.0.0, 12.22.1, 12.0.0 or 11.21.4; episerver.cms.ui to 11.37.5 or 11.37.3.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
NuGetepiserver.cms.corepkg:nuget/episerver.cms.coreOther threats | Affected
| Fixed in
|
NuGetepiserver.cms.uipkg:nuget/episerver.cms.uiOther threats | Affected
| Fixed in
|
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
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)
References
- nvd.nist.gov/vuln/detail/CVE-2025-27801 (opens in a new tab)
- api.nuget.optimizely.com/packages/episerver.cms.core/11.21.4 (opens in a new tab)
- api.nuget.optimizely.com/packages/episerver.cms.core/12.22.1 (opens in a new tab)
- r.sec-consult.com/optimizely (opens in a new tab)
- support.optimizely.com/hc/en-us/articles/30886353301645-2025-Optimizely-CMS-11-PaaS-release-notes (opens in a new tab)
- support.optimizely.com/hc/en-us/articles/37757063222029-2024-Optimizely-CMS-12-PaaS-release-notes (opens in a new tab)
- seclists.org/fulldisclosure/2025/Aug/18 (opens in a new tab)