CVE-2025-57756 in Contao
Summary
by MITRE • 08/28/2025
Contao is an Open Source CMS. In versions starting from 4.9.14 and prior to 4.13.56, 5.3.38, and 5.6.1, protected content elements that are rendered as fragments are indexed and become publicly available in the front end search. This issue has been patched in versions 4.13.56, 5.3.38, and 5.6.1. A workaround involves disabling the front end search.
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Analysis
by VulDB Data Team • 08/28/2025
The vulnerability identified as CVE-2025-57756 affects Contao, an open-source content management system that serves millions of websites worldwide. This security flaw represents a critical information disclosure issue where protected content elements are inadvertently exposed through the front-end search functionality. The vulnerability impacts multiple version ranges including 4.9.14 through 4.13.55, 5.3.0 through 5.3.37, and 5.6.0 through 5.6.0, creating a substantial attack surface across the Contao ecosystem. The flaw specifically manifests when content elements rendered as fragments are indexed by the search engine, allowing unauthorized users to access protected information through search queries. This issue directly violates fundamental security principles of access control and information hiding, as sensitive content that should remain restricted becomes discoverable through legitimate search mechanisms.
The technical root cause of this vulnerability lies in the improper handling of protected content within the search indexing process. When content elements are configured as fragments and subsequently processed by the front-end search functionality, the system fails to properly check access permissions before including these elements in the search index. This represents a classic case of insufficient access control validation, which can be categorized under CWE-284 Access Control Flaws, specifically involving inadequate privilege checking during content retrieval operations. The vulnerability demonstrates a failure in the principle of least privilege where protected resources are exposed beyond their intended access boundaries. The search indexing mechanism does not properly filter out content that should be restricted based on user roles or permissions, creating an information leakage channel that bypasses normal access control mechanisms.
The operational impact of this vulnerability extends far beyond simple information disclosure, as it fundamentally undermines the security model of Contao installations. Attackers can leverage this flaw to discover sensitive content that should remain private, potentially including administrative interfaces, restricted user data, confidential documents, or proprietary information. The vulnerability affects not just individual websites but entire organizations that rely on Contao for content management, as the exposure can occur across multiple sites within the same installation. This type of vulnerability aligns with ATT&CK technique T1213 Data from Information Repositories, where adversaries extract sensitive information from repositories that are improperly secured. The impact is particularly severe because the vulnerability affects the search functionality that is typically considered a legitimate and necessary feature, making the exploitation less obvious and more difficult to detect.
Organizations affected by this vulnerability should implement immediate remediation measures including upgrading to patched versions 4.13.56, 5.3.38, and 5.6.1, which contain the necessary fixes to prevent protected content from being indexed. The suggested workaround of disabling front-end search provides a temporary mitigation but significantly impacts user experience and website functionality. Security teams should conduct comprehensive audits of their Contao installations to identify any potential exposure that may have occurred during the vulnerable version period. The vulnerability highlights the importance of thorough security testing of search and indexing features, particularly in content management systems where content access control is paramount. Additionally, organizations should consider implementing additional monitoring for unusual search patterns that might indicate exploitation attempts. This vulnerability underscores the critical need for security considerations in all aspects of content management systems, particularly in features that interact with user-facing interfaces and information retrieval mechanisms.