Umbraco CMS vulnerabilities

An arbitrary file upload vulnerability in Umbraco CMS v16.3.3 allows attackers to execute arbitrary code by uploading a crafted PDF file. The supplier disputes this, stating that file validation is the administrator's responsibility and that PDF JavaScript runs in an isolated sandbox.

Umbraco is an ASP.NET CMS. Prior to versions 13.14.0 and 17.4.0, some Surface Controllers in the CMS fail to validate redirect URLs, making Razor templates that derive 'RedirectUrl' from user-controlled query parameters vulnerable to malicious redirect attacks.

A server-side request forgery vulnerability was found in Umbraco CMS v8.14.1. Attackers can manipulate baseUrl parameters in multiple dashboard and help controller endpoints, such as GetContextHelpForPage, GetRemoteDashboardContent, and GetRemoteDashboardCss, to trigger unauthorized server-side requests to external hosts.

A stored cross-site scripting (XSS) vulnerability in Umbraco CMS v14.3.1 allows attackers to execute arbitrary web scripts or HTML via a crafted payload. NOTE: This has been disputed by the vendor since this potential attack is only possible via authenticated users who have been manually allowed access to the CMS. There was a deliberate decision made not to apply HTML sanitization at the product level.

Umbraco, an ASP.NET CMS, can under rare conditions allow unauthorized users access to admin-level permissions after a restart. This vulnerability was patched in versions 10.6.1, 11.4.2, and 12.0.1.