A Server-side Template Injection (SSTI) vulnerability exists in Nystudio107 Seomatic 3.4.12 in src/helpers/UrlHelper.php via the host header.

A cross-site scripting (XSS) vulnerability in the SEOmatic plugin 3.4.10 for Craft CMS 3 allows remote attackers to inject arbitrary web script via a GET to /index.php?action=seomatic/file/seo-file-link with url parameter containing the base64 encoded URL of a malicious web page / file and fileName parameter containing an arbitrary filename with the intended content-type to be rendered in the user's browser as the extension.

In the SEOmatic plugin up to 3.4.11 for Craft CMS 3, it is possible for unauthenticated attackers to perform a Server-Side Template Injection, allowing for remote code execution.

In the SEOmatic plugin before 3.2.49 for Craft CMS, helpers/DynamicMeta.php does not properly sanitize the URL. This leads to Server-Side Template Injection and credentials disclosure via a crafted Twig template after a semicolon.

A Server Side Template Injection (SSTI) was discovered in the SEOmatic plugin before 3.1.4 for Craft CMS, because requests that don't match any elements incorrectly generate the canonicalUrl, and can lead to execution of Twig code.