CVE-2026-13601

Name	CVE-2026-13601
Description	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.
Source	CVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)
References	DLA-4647-1, DSA-6319-1
Debian Bugs	1136299

Vulnerable and fixed packages

The table below lists information on source packages.

Source Package	Release	Version	Status
yelp (PTS)	bullseye	3.38.3-1	vulnerable
	bullseye (security)	3.38.3-1+deb11u2	fixed
	bookworm	42.2-1+deb12u1	vulnerable
	bookworm (security)	42.2-1+deb12u2	fixed
	trixie	42.2-4	vulnerable
	trixie (security)	42.2-4+deb13u1	fixed
	forky, sid	49.1-1	fixed

The information below is based on the following data on fixed versions.

Package	Type	Release	Fixed Version	Origin	Debian Bugs
yelp	source	bullseye	3.38.3-1+deb11u2	DLA-4647-1
yelp	source	bookworm	42.2-1+deb12u2	DSA-6319-1
yelp	source	trixie	42.2-4+deb13u1	DSA-6319-1
yelp	source	(unstable)	49.1-1		1136299

Notes

https://blogs.gnome.org/mcatanzaro/2026/05/11/flatpak-sandbox-escape-via-yelp/
https://gitlab.gnome.org/GNOME/yelp/-/work_items/238
Fixed by: https://gitlab.gnome.org/GNOME/yelp/-/commit/d220aa2f754eed4e6a006a4acaa68b31892dea2b (49.1)
Fixed by: https://gitlab.gnome.org/GNOME/yelp/-/commit/c8c8244c8a812860782d635890c9b6c43ecc2639 (49.1)