CVE-2025-57759 in Contao
Summary
by MITRE • 08/28/2025
Contao is an Open Source CMS. In versions starting from 5.3.0 and prior to 5.3.38 and 5.6.1, under certain conditions, back end users may be able to edit fields of pages and articles without having the necessary permissions. This issue has been patched in versions 5.3.38 and 5.6.1. There are no workarounds.
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Analysis
by VulDB Data Team • 08/28/2025
The vulnerability identified as CVE-2025-57759 affects Contao, an open-source content management system that serves as a foundation for numerous websites and web applications. This security flaw represents a critical access control bypass issue that undermines the integrity of the system's permission model. The vulnerability specifically impacts versions from 5.3.0 through 5.3.37 and 5.6.0, creating a window of exposure where unauthorized modifications can occur within the backend administrative interface. The affected system operates under a principle of least privilege where users should only be able to modify content for which they possess explicit authorization, yet this vulnerability allows for privilege escalation through improper field validation mechanisms.
The technical root cause of this vulnerability stems from insufficient input validation and access control checks within Contao's backend field editing functionality. When backend users attempt to modify page or article fields, the system fails to properly verify whether the user possesses the necessary permissions for each specific field being modified. This flaw manifests as a failure in the authorization enforcement layer, where the system does not adequately cross-reference user roles, permissions, and the specific fields being accessed. The vulnerability is particularly concerning because it operates silently, allowing unauthorized modifications without triggering security alerts or audit trails. This behavior aligns with CWE-285, which addresses improper authorization issues in software systems, and demonstrates the classic pattern of insufficient access control validation that can lead to privilege escalation attacks.
The operational impact of this vulnerability extends beyond simple unauthorized content modification, potentially enabling attackers to manipulate critical website components and compromise the overall integrity of the content management environment. Backend users with limited privileges can exploit this vulnerability to alter fields that should be restricted to administrators or specific user groups, potentially leading to data corruption, information disclosure, or the introduction of malicious content. The vulnerability affects the core administrative functionality of Contao, making it particularly dangerous as it undermines the trust model that users place in the system's permission controls. This type of access control bypass can be leveraged by both internal threat actors and external attackers who have gained backend access, creating a significant risk to website integrity and user data protection. The lack of available workarounds forces organizations to immediately apply the vendor-provided patches to mitigate the risk, as there are no alternative methods to secure the system without upgrading to the patched versions.
Organizations utilizing Contao systems must prioritize immediate remediation of this vulnerability by upgrading to versions 5.3.38 or 5.6.1, as no alternative mitigation strategies exist. The vulnerability's classification as an access control bypass aligns with ATT&CK technique T1078 which covers valid accounts and privilege escalation, and the lack of workarounds means that organizations cannot implement temporary fixes while maintaining system functionality. Security teams should conduct comprehensive audits of their Contao installations to identify any potential exploitation attempts, particularly focusing on backend access logs and modification records. The vulnerability demonstrates the critical importance of maintaining up-to-date software in content management systems where administrative privileges can have far-reaching consequences for entire websites and their user bases. Organizations should also implement enhanced monitoring for unauthorized field modifications and establish incident response procedures specifically addressing potential privilege escalation scenarios. This vulnerability serves as a reminder of the importance of proper access control implementation and the need for thorough security testing of administrative interfaces in web applications.