The vulnerability arises from an overly permissive Content Security Policy in Yelp's yelp-xsl stylesheet, allowing a malicious Flatpak application to 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 sandbox isolation. This causes Yelp to evaluate local XML inclusions and disclose arbitrary user-readable files on the host system via remote CSS resource requests. Exploitation does not require privileges on Yelp or additional user interaction beyond running the malicious Flatpak app. The vulnerability is a cross-boundary information disclosure and a regression of a previously fixed issue (CVE-2025-3155). The fix is applied exclusively in the Yelp application package. Red Hat Enterprise Linux 9 versions prior to the update are affected, and a security update is available to remediate the issue.

This vulnerability allows a sandboxed Flatpak application to bypass its intended isolation and cause Yelp to disclose arbitrary user-readable files from the host system. The impact is limited to confidentiality as there is no demonstrated effect on integrity or availability. The vulnerability does not require elevated privileges or user interaction beyond running the malicious Flatpak application. This cross-boundary information disclosure could lead to unauthorized exposure of sensitive information on affected systems.

A security update for the Yelp package is available from Red Hat and should be applied to fully remediate this vulnerability. No other mitigations meeting Red Hat's standards for usability and stability are currently available. Systems are protected once the updated Yelp package is installed. Users should follow Red Hat's official guidance for applying the update as detailed in their advisory.