Ektron CMS authentication bypass
Description
Episerver CMS (formerly Ektron CMS) is an ASP.NET-based web content management system and digital marketing platform.
Ektron CMS version 9.20 SP2 and earlier versions contain an authentication bypass vulnerability that allows remote attackers to access administrative functionality without valid credentials. The vulnerability stems from improper validation of the HTTP Referer header, which the application uses as a security control. By manipulating this header, attackers can gain unauthorized access to sensitive administrative pages, including the user activation endpoint (/WorkArea/activateuser.aspx).
Remediation
Upgrade Ektron CMS to a patched version that includes security fix EKTR-508 (Security enhancement for re-enabling a user). This patch addresses the improper reliance on the Referer header for authentication decisions.
If immediate patching is not possible, implement the following interim mitigations:
1. Restrict network access to administrative pages (/WorkArea/*) using IP allowlisting at the web server or firewall level
2. Implement additional authentication checks that do not rely on client-controlled headers
3. Monitor access logs for suspicious requests to administrative endpoints with unusual Referer headers
4. Disable or restrict the user activation functionality until the patch can be applied
After upgrading, verify that administrative pages properly enforce authentication and cannot be accessed by manipulating HTTP headers.