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Yelp CVE-2026-13601

| EUVDEUVD-2026-40066 MEDIUM
Protection Mechanism Failure (CWE-693)
2026-06-29 secalert@redhat.com GHSA-f4vh-qr53-q5gv
6.5
CVSS 3.1 · NVD
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Severity by source

NVD PRIMARY
6.5 MEDIUM
AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N
vuln.today AI
7.1 HIGH

Requires a locally-running sandboxed app (AV:L) but no host privileges or interaction (PR:N/UI:N); sandbox-to-host escape changes scope (S:C) and leaks files (C:H) without integrity/availability impact.

3.1 AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N
4.0 AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:N/SA:N
SUSE
7.1 HIGH
AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N
Red Hat
7.1 HIGH
qualitative

Primary rating from NVD.

CVSS VectorNVD

Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Changed
Confidentiality
High
Integrity
None
Availability
None

Lifecycle Timeline

3
Severity Changed
Jul 08, 2026 - 03:37 NVD
HIGH MEDIUM
CVSS changed
Jul 08, 2026 - 03:37 NVD
7.1 (HIGH) 6.5 (MEDIUM)
Analysis Generated
Jun 29, 2026 - 10:32 vuln.today

DescriptionNVD

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.

AnalysisAI

Sandbox-escaping information disclosure in Yelp (the GNOME help viewer) lets a malicious Flatpak application read arbitrary user-readable files on the host. By using the OpenURI portal to open crafted help content that embeds an untrusted CSS stylesheet inside a structured SVG document, an attacker abuses an overly permissive Content Security Policy supplied by yelp-xsl to force Yelp to evaluate local XML inclusions and exfiltrate file contents via remote CSS resource requests, defeating Flatpak's intended isolation. The flaw was disclosed publicly (GNOME developer blog by Michael Catanzaro, May 2026) and tracked by Red Hat; no public exploit identified at time of analysis and it is not listed in CISA KEV.

Technical ContextAI

The root cause is classified as CWE-693 (Protection Mechanism Failure): the CSP that yelp-xsl ships for rendered help documents is too permissive, so Yelp's WebKit-based rendering pipeline does not block externally-controlled resource loads or local XML entity/inclusion processing that a hardened policy would prevent. The attack composes several desktop technologies - Flatpak's portal system (specifically the OpenURI portal, the sanctioned cross-sandbox mechanism for asking the host to open a URI), Yelp's Mallard/DocBook XML help rendering, and SVG/CSS processing. An SVG document is used as a structured carrier so that an embedded CSS stylesheet and local XML inclusions are evaluated in Yelp's (host-side, unsandboxed) context; the contents of user-readable host files are then leaked outbound through remote CSS resource fetches (a classic CSS/XML-inclusion side channel). Because Yelp runs outside the calling app's Flatpak sandbox, evaluating attacker-controlled content there constitutes a confidentiality scope change from the sandbox to the host.

RemediationAI

Upstream fix available (PR/commit); released patched version not independently confirmed - apply the distribution package update that incorporates GNOME GitLab commit c8c8244c8a812860782d635890c9b6c43ecc2639 for Yelp (and the corresponding yelp-xsl CSP tightening), tracking your distro's advisory via the Red Hat entry at https://access.redhat.com/security/cve/CVE-2026-13601 and Bugzilla 2494110 (https://bugzilla.redhat.com/show_bug.cgi?id=2494110) for the exact patched build for your OS. Until the package is updated, reduce exposure by only installing Flatpak applications from trusted sources and review/limit which apps are allowed to use the OpenURI portal - restricting or denying OpenURI access for untrusted apps (e.g., via portal/permission configuration) prevents the delivery path, at the cost of breaking legitimate 'open in help/browser' behavior for those apps. Avoid setting Yelp as the handler for content originating from untrusted sandboxed applications; the side effect is that in-app help links from those apps will no longer open automatically. Consult the technical analysis at https://blogs.gnome.org/mcatanzaro/2026/05/11/flatpak-sandbox-escape-via-yelp/ for details before relying on workarounds.

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Vendor StatusVendor

SUSE

Severity: Important
Product Status
SUSE Linux Enterprise High Performance Computing 15 SP4-ESPOS Affected
SUSE Linux Enterprise High Performance Computing 15 SP4-LTSS Affected
SUSE Linux Enterprise High Performance Computing 15 SP5-ESPOS Affected
SUSE Linux Enterprise High Performance Computing 15 SP5-LTSS Affected
SUSE Linux Enterprise Module for Desktop Applications 15 SP7 Affected

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CVE-2026-13601 vulnerability details – vuln.today

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