CVE-2021-43991: Kentico Xperience

Medium severity, CVSS 5.4. EPSS: 0.6% chance of exploitation in the next 30 days.

The Kentico Xperience CMS version 13.0 – 13.0.43 is vulnerable to a persistent Cross-Site Scripting (XSS) vulnerability (also known as Stored or Second-Order XSS). Persistent XSS vulnerabilities occur when the application stores and retrieves client supplied data without proper handling of dangerous content. This type of XSS vulnerability is exploited by submitting malicious script content to the application which is then retrieved and executed by other application users. The attacker could exploit this to conduct a range of attacks against users of the affected application such as session hijacking, account take over and accessing sensitive data.

Affected products

• Kentico Xperience: from 13.0.0, up to and including 13.0.43

Published 2021-12-03. Last modified 2026-06-17.