Contao: Improper access control in the preview links module
Medium · CVSS 4.3
`core-bundle/config/services.yaml` registers the preview access voter with the class `Contao\CoreBundle\Security\Voter\DataContainer\PreviewAccessVoter`, but the class shipped on disk is named `PreviewVoter`. Symfony resolves the class with `getReflectionClass($class, false)`, gets `null`, silently skips the interface based autoconfiguration that would have tagged it as a voter, and the now untagged private service is removed when the container is compiled. The application boots without a warning, and the ownership rule in `PreviewVoter::hasAccess()` is never executed.
Remediation
Upgrade contao/core-bundle to 5.7.12 or later.
Affected PHP branches
See the source advisory.
Source: GitHub Global Security Advisories (Composer ecosystem) · retrieved 2026-10-22T10:19:14-04:00 · https://github.com/advisories/GHSA-q6wp-fr43-gm9v