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.

Format string vulnerability in the window_error function in yelp-window.c in yelp in Gnome after 2.19.90 and before 2.24 allows remote attackers to execute arbitrary code via format string specifiers in an invalid URI on the command line, as demonstrated by use of yelp within (1) man or (2) ghelp URI handlers in Firefox, Evolution, and unspecified other programs.