Answer in brief
CVE-2026-107850 records a Medium severity (CVSS 4.3) vulnerability in Contao: Improper access control in the preview links module. The current sources do not mark it as known exploited. The current feed maps contao/core-bundle (composer), contao/contao (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 4.3. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps contao/core-bundle (composer), contao/contao (generic). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| contao/core-bundlecomposer | >=5.7.1,<5.7.12 | 5.7.12 |
| contao/contaogeneric | >=5.7.1 <5.7.12 | 5.7.12 |
Published upstream
Oct 9, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Oct 9, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Oct 9, 2026
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module can list every tl_preview_link record, obtain signed share URLs created by other users, and use them to view unpublished pages with showUnpublished despite lacking page permission.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.
Quoted source text, attributed separately from HOL analysis.