CVE-2020-36891 Kentico Xperience <= 12.0.49 File Upload Stored XSS
Attackers can upload malicious files with spoofed MIME types to execute scripts in users' browsers via stored XSS in Kentico Xperience.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- None listed
What is CVE-2020-36891?
CVE-2020-36891 is a medium-severity cross-site scripting vulnerability in Kentico Xperience, published on 18 Dec 2025. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.
Official description
A stored cross-site scripting vulnerability in Kentico Xperience allows attackers to upload files with spoofed Content-Type that do not match file extensions. Attackers can exploit this vulnerability by uploading malicious files with manipulated MIME types, allowing malicious scripts to execute in users' browsers.
Weakness: CWE-79
Which versions are affected by CVE-2020-36891?
It affects 1 product.
Products include Kentico Xperience.
How do I fix CVE-2020-36891?
No fix has been published for CVE-2020-36891 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-2020-36891 being exploited?
There is no known exploitation of CVE-2020-36891 in the wild and no public exploit code.
Other vulnerabilities in Kentico Xperience
- CVE-2025-2746 Kentico Xperience CMS Authentication Bypass Using an Alternate Path or Channel
- CVE-2025-2747 Kentico Xperience CMS Authentication Bypass Using an Alternate Path or Channel
- CVE-2019-10068 Kentico Xperience Deserialization of Untrusted Data
- CVE-2025-2749 Kentico Xperience Path Traversal
- CVE-2017-17736 Missing authorization in n/a
Sources
Also known as GHSA-fcwr-xg8x-ppc3.