Kentico Xperience: file access flaw under attack

What is affected

Kentico Xperience is mostly run by companies, schools and public bodies, not on home computers. You are unlikely to have it yourself, but organisations that hold your data may. Breaches that start with flaws like this one are how personal data ends up leaked.

Kentico Xperience contains a path traversal vulnerability that could allow an authenticated user's Staging Sync Server to upload arbitrary data to path relative locations.

What an attacker can do

This is a file access flaw. It lets an attacker read or write files they should never reach, such as configuration files that hold passwords, or upload a malicious file that the system then runs.

How it is reached

Over the internet or network

Access the attacker needs

An administrator account

Does the victim have to do something?

No, works without the victim doing anything

What to do

1. At home: nothing to install. Keep your own devices updated and use a different password for every service, so that a breach at one organisation does not open your other accounts.
2. If you administer Kentico Xperience at work: apply the vendor's fix or mitigation now and review logs for signs of compromise, because the flaw was being exploited before it was listed.
3. If the product is past its support date and no fix exists, take it off the internet or retire it.

Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

Vendor advisories and fixes

• devnet.kentico.comdevnet.kentico.com/download/hotfixes

How urgent is it

CISA added this vulnerability to its Known Exploited Vulnerabilities catalogue on April 20, 2026, which means there is reliable evidence of attacks in the wild. US federal agencies must fix it by May 4, 2026, a deadline that has already passed. That deadline does not bind anyone else, but it shows how seriously the agency rates it.

The EPSS model estimates a 4.1% probability that this flaw will be exploited somewhere in the next 30 days. That is higher than 90% of all scored vulnerabilities.

Its CVSS severity score is 7.2 out of 10 (high), as recorded in the US National Vulnerability Database.

Technical description

An authenticated remote code execution in Kentico Xperience allows authenticated users Staging Sync Server to upload arbitrary data to path relative locations. This results in path traversal and arbitrary file upload, including content that can be executed server side leading to remote code execution.This issue affects Kentico Xperience through 13.0.178.