Access Control Flaw in Contao CMS Affects Core Functionality
CVE-2026-107850

4.3MEDIUM

Key Information:

Vendor

Contao

Status
Contao
Vendor
CVE Published:
9 October 2026

What is CVE-2026-107850?

The vulnerability in Contao CMS arises from an access control flaw in the preview_link module. Non-admin backend users can exploit this issue to access and list all tl_preview_link records, which allows them to obtain signed share URLs created by other users. This enables unauthorized viewing of unpublished pages through the showUnpublished feature, bypassing necessary page permissions. The root cause lies in the registration of the PreviewAccessVoter, which fails to enforce ownership properly. Users are encouraged to upgrade to version 5.7.12 to remediate this issue.

Affected Version(s)

contao >= 5.7.1, < 5.7.12

References

https://github.com/contao/contao/security/advisories/GHSA...
x_refsource_CONFIRM
https://github.com/contao/contao/commit/6b483d380a4b2dc61...
x_refsource_MISC
https://github.com/contao/contao/releases/tag/5.7.12
x_refsource_MISC

CVSS V3.1

Score:
4.3
Severity:
MEDIUM
Confidentiality:
Low
Integrity:
None
Availability:
Low
Attack Vector:
Network
Attack Complexity:
Low
Privileges Required:
Low
User Interaction:
None
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

.