Description
Contao is an Open Source CMS. From version 5.7.1 until 5.7.12, core-bundle/config/services.yaml registers the preview access voter as Contao\CoreBundle\Security\Voter\DataContainer\PreviewAccessVoter although the shipped class is PreviewVoter. Symfony therefore omits voter autoconfiguration and removes the private service, so PreviewVoter::hasAccess() never enforces ownership. A non-admin backend user with the preview_link module can list every tl_preview_link record, obtain signed share URLs created by other users, and use them to view unpublished pages with showUnpublished despite lacking page permission. The advisory does not establish editing or deletion of foreign links. This issue is fixed in version 5.7.12.
Published: 2026-10-09
Score: 4.3 Medium
EPSS: n/a
KEV: No
AI Analysis

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Remediation

No vendor fix or workaround currently provided.

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Tracking

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Advisories
Source ID Title
Github GHSA Github GHSA GHSA-q6wp-fr43-gm9v Contao: Improper access control in the preview links module
History

Fri, 09 Oct 2026 21:45:00 +0000

Type Values Removed Values Added
First Time appeared Contao
Contao contao
Vendors & Products Contao
Contao contao

Fri, 09 Oct 2026 20:45:00 +0000

Type Values Removed Values Added
Description Contao is an Open Source CMS. From version 5.7.1 until 5.7.12, core-bundle/config/services.yaml registers the preview access voter as Contao\CoreBundle\Security\Voter\DataContainer\PreviewAccessVoter although the shipped class is PreviewVoter. Symfony therefore omits voter autoconfiguration and removes the private service, so PreviewVoter::hasAccess() never enforces ownership. A non-admin backend user with the preview_link module can list every tl_preview_link record, obtain signed share URLs created by other users, and use them to view unpublished pages with showUnpublished despite lacking page permission. The advisory does not establish editing or deletion of foreign links. This issue is fixed in version 5.7.12.
Title Contao: Improper access control in the preview links module
Weaknesses CWE-639
CWE-862
References
Metrics cvssV3_1

{'score': 4.3, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N'}


cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-10-09T20:25:02.286Z

Reserved: 2026-10-08T22:34:49.292Z

Link: CVE-2026-107850

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-10-09T21:17:02.770

Modified: 2026-10-09T21:17:02.770

Link: CVE-2026-107850

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-10-09T21:30:12Z

Weaknesses
  • CWE-639

    Authorization Bypass Through User-Controlled Key

  • CWE-862

    Missing Authorization