Contao up to 5.7.11 TableAccessVoter TableAccessVoter.php hasAccessToModule tokenHash improper authorization

Summaryinfo

A vulnerability identified as critical has been detected in Contao up to 5.7.11. The impacted element is the function TableAccessVoter::hasAccessToModule of the file core-bundle/src/Security/Voter/DataContainer/TableAccessVoter.php of the component TableAccessVoter. This manipulation of the argument tokenHash causes improper authorization. This vulnerability is registered as CVE-2026-107851. Remote exploitation of the attack is possible. No exploit is available. You should upgrade the affected component.

Detailsinfo

A vulnerability was found in Contao up to 5.7.11. It has been declared as critical. Affected by this vulnerability is the function TableAccessVoter::hasAccessToModule of the file core-bundle/src/Security/Voter/DataContainer/TableAccessVoter.php of the component TableAccessVoter. The manipulation of the argument tokenHash with an unknown input leads to a improper authorization vulnerability. The CWE definition for the vulnerability is CWE-285. The product does not perform or incorrectly performs an authorization check when an actor attempts to access a resource or perform an action. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

Contao is an Open Source CMS. From version 5.7.0 until 5.7.12, TableAccessVoter::hasAccessToModule() in core-bundle/src/Security/Voter/DataContainer/TableAccessVoter.php caches authorization decisions using only $tokenHash, a hash of the user's security token, and omits the table returned by getDataSource(). If one request first checks a table allowed to the user and then a different denied table, the voter can reuse the allowed result, while DefaultDataContainerVoter can convert an incorrect abstention into a grant. A low-privileged backend user can consequently read, create, update, or delete records in tables outside assigned module permissions, including tables containing member or newsletter-subscriber data. This issue is fixed in version 5.7.12.

The advisory is shared at github.com. This vulnerability is known as CVE-2026-107851 since 10/09/2026. The exploitation appears to be easy. The attack can be launched remotely. Technical details are known, but no exploit is available. MITRE ATT&CK project uses the attack technique T1548.002 for this issue.

By approaching the search of inurl:core-bundle/src/Security/Voter/DataContainer/TableAccessVoter.php it is possible to find vulnerable targets with Google Hacking.

Upgrading to version 5.7.12 eliminates this vulnerability.

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Productinfo

Name

• Contao

Version

• 5.7.0
• 5.7.1
• 5.7.2
• 5.7.3
• 5.7.4
• 5.7.5
• 5.7.6
• 5.7.7
• 5.7.8
• 5.7.9
• 5.7.10
• 5.7.11

Website

• Product: https://github.com/contao/contao/

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