YesWiki before 4.6.7 Unauthenticated SSRF via syndication Action

YesWiki before 4.6.7 contains an unauthenticated server-side request forgery vulnerability that allows remote attackers to make the server fetch arbitrary URLs by supplying a syndication action through the render handler's content parameter. Attackers can target internal hosts and ports, read back fetched feed content in the rendered page, and cause feed enclosures to be downloaded into the files directory.