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 Flatpaks 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.
Weakness
The product does not use or incorrectly uses a protection mechanism that provides sufficient defense against directed attacks against the product.
Affected Software
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Enterprise_linux | Redhat | 6.0 (including) | 6.0 (including) |
| Enterprise_linux | Redhat | 7.0 (including) | 7.0 (including) |
| Enterprise_linux | Redhat | 8.0 (including) | 8.0 (including) |
| Enterprise_linux | Redhat | 9.0 (including) | 9.0 (including) |
| Yelp | Ubuntu | esm-infra-legacy/xenial | * |
| Yelp | Ubuntu | esm-infra/bionic | * |
| Yelp | Ubuntu | esm-infra/focal | * |
| Yelp | Ubuntu | jammy | * |
| Yelp | Ubuntu | noble | * |
| Yelp | Ubuntu | questing | * |
| Yelp | Ubuntu | resolute | * |
| Yelp | Ubuntu | upstream | * |
Related Attack Patterns
- https://cwe.mitre.org/data/definitions/1.html
- https://cwe.mitre.org/data/definitions/107.html
- https://cwe.mitre.org/data/definitions/127.html
- https://cwe.mitre.org/data/definitions/17.html
- https://cwe.mitre.org/data/definitions/20.html
- https://cwe.mitre.org/data/definitions/22.html
- https://cwe.mitre.org/data/definitions/237.html
- https://cwe.mitre.org/data/definitions/36.html
- https://cwe.mitre.org/data/definitions/477.html
- https://cwe.mitre.org/data/definitions/480.html
- https://cwe.mitre.org/data/definitions/51.html
- https://cwe.mitre.org/data/definitions/57.html
- https://cwe.mitre.org/data/definitions/59.html
- https://cwe.mitre.org/data/definitions/65.html
- https://cwe.mitre.org/data/definitions/668.html
- https://cwe.mitre.org/data/definitions/74.html
- https://cwe.mitre.org/data/definitions/87.html
References
- https://access.redhat.com/security/cve/CVE-2026-13601
- https://blogs.gnome.org/mcatanzaro/2026/05/11/flatpak-sandbox-escape-via-yelp/
- https://bugzilla.redhat.com/show_bug.cgi?id=2494110
- https://gitlab.gnome.org/GNOME/yelp/-/commit/c8c8244c8a812860782d635890c9b6c43ecc2639
- https://gitlab.gnome.org/GNOME/yelp/-/work_items/238
- https://access.redhat.com/security/cve/CVE-2026-13601
- https://bugzilla.redhat.com/show_bug.cgi?id=2494110
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-13601.json