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VulnerabilityPublished Updated

CVE-2025-27800: The Episerver Content Management System (CMS) by Optimizely was affected by multiple Stored

Source GCVE Database

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Authoritative record:CVE-2025-27800· Medium 4.8

Not known to be exploited · CVSS 4.8 Medium · fixed in 12.22.1 : update Episerver Content Management System (CMS) when convenient.

Data as of 29 Oct 2026, 22:52 UTC

CVSS 4.0 base score
4.8Medium
How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none
CVSS scores by source
CNA (SEC-VLab)CVSS 4.04.8
CNA (SEC-VLab)CVSS 3.14.8
Patch
Available – fixed in 12.22.1, 11.21.4, 11.37.5 +1
CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 28 Jul 2025

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq 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 12.22.1 or 11.21.4; episerver.cms.ui to 11.37.5 or 11.37.3.

Affected software

ProductAffectedFixed in
NuGetepiserver.cms.corepkg:nuget/episerver.cms.coreOther threatsAffected
  • <11.21.4
  • <12.22.1
Fixed in
  • 11.21.4
  • 12.22.1
NuGetepiserver.cms.uipkg:nuget/episerver.cms.uiOther threatsAffected
  • <11.37.5
  • <11.37.3
Fixed in
  • 11.37.5
  • 11.37.3

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. 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)

References

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