Executive brief
Concrete CMS is a popular website content management system. A flaw in the multilingual page assignment feature allows authenticated users with limited permissions to reassign which pages are translations of each other across languages and delete legitimate translation pairings, potentially disrupting public-facing site navigation and language routing for end users.
Technical details
The vulnerability is a combined authorization check bypass and CSRF token validation failure in the Backend\Page\Multilingual::assign backend action. An authenticated user who holds the Edit Page Multilingual Settings permission on a single page can exploit the lack of destination-side authorization checks and CSRF token validation to bind an arbitrary page in another locale as a source page's translation, and delete legitimate translation pairs. Attack requires authentication and the attacker must already hold multilingual editing rights on at least one page. The impact is limited to language routing and translation relationship integrity rather than data exposure. Patched in Concrete CMS version 9.5.3 and later.
Affected products
- Concrete CMS Concrete CMS before 9.5.3
Timeline
- 2026-09-15: disclosed