CVE-2026-13601
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.
Executive briefing
The source record describes: 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. The practical risk depends on whether an affected product/version is present, reachable and configured in an exploitable way. Review the affected-product evidence and linked vendor advisories before assigning exposure status.
Evidence confidence: Moderate Evidence-derived, not an exploitability verdict
Severity & attack characteristics
CVSS vector:CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N
Technical explanation & impact
The technical mechanism is not expanded beyond the source description unless a referenced advisory supplies additional evidence. Read the linked vendor/CERT advisories for root-cause detail.
Potential impact must be interpreted from the published CVSS impact metrics and the affected component. A CVSS impact score is not proof that a particular asset is exploitable.
Weakness classification
CWE-693Affected products and versions
Products below are parsed from NVD vulnerable CPE configuration entries. Version boundaries are shown as published; verify applicability with the vendor.
| Vendor | Product | Version evidence |
|---|---|---|
| redhat | enterprise_linux | CPE version 6.0 · CPE version 7.0 · CPE version 8.0 · CPE version 9.0 |
| gnome | yelp | before 49.1 |
Remediation & validation
- Identify exposure by comparing the affected product and version ranges with your asset inventory, SBOM and externally exposed services.
- Review the linked vendor security advisory or patch notes. Upgrade to a vendor-confirmed fixed release; do not infer a fixed version from the CVE description.
- Until patched, consider restricting network access or disabling the affected feature where operationally safe. These are temporary controls, not a substitute for a vendor fix.
- Validate the remediation with a version check and vulnerability rescan, then retain change evidence.
No fixed version is displayed unless it is explicitly established by a vendor advisory. Follow the vendor's release notes for exact product and branch applicability.
Vendor advisories, patches & exploit references
- https://access.redhat.com/errata/RHSA-2026:47177 VENDOR secalert@redhat.com
- https://access.redhat.com/errata/RHSA-2026:47178 VENDOR secalert@redhat.com
- https://access.redhat.com/errata/RHSA-2026:54539 VENDOR secalert@redhat.com
- https://access.redhat.com/errata/RHSA-2026:54540 VENDOR secalert@redhat.com
- https://access.redhat.com/errata/RHSA-2026:54605 VENDOR secalert@redhat.com
- https://access.redhat.com/errata/RHSA-2026:54624 VENDOR secalert@redhat.com
- https://access.redhat.com/errata/RHSA-2026:54637 VENDOR secalert@redhat.com
- https://access.redhat.com/errata/RHSA-2026:54666 VENDOR secalert@redhat.com
- https://access.redhat.com/errata/RHSA-2026:57417 VENDOR secalert@redhat.com
- https://access.redhat.com/security/cve/CVE-2026-13601 ADVISORY secalert@redhat.com
- https://blogs.gnome.org/mcatanzaro/2026/05/11/flatpak-sandbox-escape-via-yelp/ ADVISORY secalert@redhat.com
- https://bugzilla.redhat.com/show_bug.cgi?id=2494110 ADVISORY secalert@redhat.com
- https://gitlab.gnome.org/GNOME/yelp/-/commit/c8c8244c8a812860782d635890c9b6c43ecc2639 PATCH secalert@redhat.com
- https://gitlab.gnome.org/GNOME/yelp/-/work_items/238 ADVISORY secalert@redhat.com
- https://access.redhat.com/errata/RHSA-2026:47177 VENDOR 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
- https://access.redhat.com/errata/RHSA-2026:47178 VENDOR 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
- https://access.redhat.com/errata/RHSA-2026:54539 VENDOR 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
- https://access.redhat.com/errata/RHSA-2026:54540 VENDOR 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
- https://access.redhat.com/errata/RHSA-2026:54605 VENDOR 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
- https://access.redhat.com/errata/RHSA-2026:54624 VENDOR 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
- https://access.redhat.com/errata/RHSA-2026:54637 VENDOR 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
- https://access.redhat.com/errata/RHSA-2026:54666 VENDOR 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
- https://access.redhat.com/errata/RHSA-2026:57417 VENDOR 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
- https://access.redhat.com/security/cve/CVE-2026-13601 ADVISORY 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
- https://bugzilla.redhat.com/show_bug.cgi?id=2494110 ADVISORY 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-13601.json ADVISORY 0b0ca135-0b70-47e7-9f44-1890c2a1c46c