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The vulnerability lies within the way Contao CMS handles search indexing and authorization filtering for protected pages through the `ModuleSearch` component. Specifically, the system determines whether to filter protected pages out of public search results based on the global configuration parameter contao.search.index_protected. However, the actual authorization state and data reside on a per-row basis within the database table tl_search. When an administrator changes the configuration setting or turns off indexing of protected pages, the system removes the dynamic filter applied during query execution without purging or removing the already indexed database rows. Consequently, protected pages that were previously indexed while the setting was enabled continue to persist in the `tl_search` table. When unauthenticated visitors perform a search query on the public website, these stale search index records are retrieved and rendered, exposing sensitive information such as page s, URLs, and contextual content snippets. Although the underlying web pages themselves still correctly enforce access control and return a 401 Unauthorized response when directly requested, the information disclosure via the frontend search mechanism bypasses expected confidentiality boundaries for member-only content. This flaw requires administrators to manually clear and rebuild the search index whenever configuration parameters regarding protected content indexing are modified, or rely on patched core bundles that automatically invalidate stale search records. Security researchers have noted that improper handling of state synchronization between configuration parameters and cached database indexes frequently leads to this class of information leakage across various content management systems. Remediation involves upgrading to patched core releases and ensuring that database maintenance routines properly prune restricted records upon policy changes.
DailyCVE Form:
Platform: Contao CMS
Version: 4.x – 5.7.11
Vulnerability : Information Disclosure
Severity : Moderate
date : 2026-08-25
Prediction : Patch Released
What Undercode Say
Bash Commands and Code
Update Contao core via Composer to resolve stale index exposure composer update contao/core-bundle contao/contao --with-dependencies Clear and rebuild the frontend search index via CLI vendor/bin/contao-console contao:crawl --rebuild
Exploit: (Educational Purposes!)
GET /search?keywords=confidential+member+data HTTP/1.1 Host: vulnerable-contao-site.local User-Agent: Mozilla/5.0 Accept: text/html
An unauthenticated attacker sends a standard GET request to the frontend search endpoint using keywords matching restricted member-only pages. Even though the direct page links return a 401 response, the search results page exposes s, URLs, and snippets from the stale index.
Protection: from this CVE
Upgrade Contao core-bundle to version 5.3.50, 5.7.12, or later.
Clear and rebuild the search index immediately after changing any search configuration settings.
Restrict public access to search modules if sensitive data indexing cannot be immediately verified.
Impact
Disclosure of member-only page s, URLs, and indexed snippet text to unauthenticated remote visitors via the site search interface, compromising data confidentiality for restricted areas.
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Sources:
Reported By: github.com
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