Affected: Ubuntu:Pro:16.04:LTS: yelp, Ubuntu:Pro:18.04:LTS: yelp, Ubuntu:Pro:20.04:LTS: yelp, Ubuntu:22.04:LTS: yelp, Ubuntu:24.04:LTS: yelp, Ubuntu:25.10: yelp, Ubuntu:26.04:LTS: yelp

A flaw was found in Yelp due to an overly permissive Content Security Policy (CSP) implementation provided by yelp-xsl. A malicious Flatpak application can open crafted help content through the OpenURI portal. By embedding an untrusted CSS stylesheet within a structured SVG document, attacker-controlled content can bypass Flatpak's intended sandbox isolation, allowing Yelp to evaluate local XML inclusions and disclose arbitrary user-readable host files through remote CSS resource requests. This may result in the unauthorized disclosure of sensitive information.