Server-side Template Injection (SSTI) vulnerability in Winter CMS v.1.2.3 allows a remote attacker to execute arbitrary code via a crafted payload to the CMS Pages field and Plugin components. NOTE: the vendor disputes this because the payload could only be entered by a trusted user, such as the owner of the server that hosts Winter CMS, or a developer working for them.
The product generates a web page, but does not neutralize or incorrectly neutralizes user-controllable input that could be interpreted as a server-side include (SSI) directive.