CVE-2026-107842 in Contao
Summary
by MITRE • 10/09/2026
Contao is an Open Source CMS. From version 4.0.0 until 5.3.50 and 5.7.12, ModuleSearch can disclose protected page titles, URLs, and indexed context snippets to unauthenticated visitors when contao.search.index_protected is changed from enabled to disabled. Authorization metadata is stored per row in tl_search, but disabling the setting removes the protected-row filter without deleting rows indexed while protection was enabled. The protected pages continue to return an authorization response, so this issue exposes search metadata and indexed text rather than bypassing page access. This issue is fixed in versions 5.3.50 and 5.7.12.
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Analysis
by VulDB Data Team • 10/09/2026
The vulnerability identified within the Contao Content Management System represents a significant information disclosure flaw located specifically within the ModuleSearch component. This security defect affects multiple releases of the software, spanning from version 4.0.0 through versions 5.3.50 and 5.7.12. The core issue arises from an inconsistency in how authorization metadata is managed during the indexing process versus its enforcement during search queries. When the configuration parameter contao.search.index_protected is toggled from enabled to disabled, the system fails to properly sanitize or remove previously indexed data that was created while protection was active. This creates a state where historical index entries remain accessible despite the administrative decision to stop protecting such content in new searches, leading to unintended exposure of sensitive information.
From a technical perspective, the flaw stems from how authorization metadata is stored and filtered within the tl_search database table. The system stores this metadata on a per-row basis, allowing for granular control over which search results are visible based on page access rights. However, when an administrator disables the index_protected setting to allow public indexing of previously protected pages, the application logic removes the filter that restricts access to these rows during query execution. Crucially, this action does not trigger a cleanup process to delete or anonymize the existing indexed records for those specific pages. Consequently, unauthenticated visitors can perform search queries and retrieve metadata such as page titles, URLs, and context snippets from the index database. These data points were originally generated while the pages were restricted, meaning they contain information that was intended to be hidden from public view.
The operational impact of this vulnerability is primarily centered on unauthorized information disclosure rather than a complete bypass of access controls. It is important to note that disabling the setting does not grant unauthenticated users direct access to the protected page content itself; those pages continue to return appropriate authorization responses when accessed directly via their URLs. Instead, the attack vector exploits the search index as an indirect channel for data leakage. By querying the search module, attackers can discover which protected resources exist on the site by observing their titles and URL structures in the results. Furthermore, the indexed context snippets may reveal sensitive textual content from within those restricted pages. This type of information gathering is particularly dangerous because it allows adversaries to map out internal site structures, identify valuable targets for further attacks, or extract confidential business logic without ever needing to authenticate against the main application interface.
This vulnerability aligns with CWE-200, which defines Information Exposure, specifically falling under categories related to exposure of sensitive information through error messages or search results that are not properly filtered based on user privileges. In terms of offensive security frameworks such as MITRE ATT&CK, this behavior facilitates the Reconnaissance phase, particularly techniques involving Search Engine Discovery and Web Scraping. Attackers can leverage standard web crawlers or custom scripts to harvest these indexed snippets systematically, building a detailed profile of the organization's digital assets without triggering traditional authentication-based intrusion detection systems. The persistence of this data in the search index means that even after the configuration change is made, the risk remains until the database is explicitly cleaned or re-indexed with proper safeguards applied retroactively.
To mitigate this vulnerability and prevent further exposure, administrators must upgrade to Contao version 5.3.50 or 5.7.12 immediately if they are running affected versions. These releases contain code changes that ensure consistency between indexing policies and query filtering logic, preventing the leakage of protected metadata when settings are modified. For organizations unable to patch immediately due to operational constraints, a temporary mitigation involves manually purging the tl_search table entries associated with previously protected pages after disabling the index_protected setting. This manual cleanup ensures that no residual data from restricted content remains in the public-facing search index. Additionally, implementing strict access controls on the database layer itself can provide an additional defense-in-depth measure by ensuring that even if application logic fails to filter results correctly, direct queries against the search table remain inaccessible to unprivileged users. Regular audits of configuration changes related to security settings should also be conducted to ensure that state transitions do not leave residual data artifacts in persistent storage layers like databases or caches.