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GHSA-9ff2-p842-45wq

Contao: Cross-site request forgery in custom backend actions

Source: GitHub Advisory Database (reviewed) Low CVE-2026-107848

Packages

EcosystemPackageAffectedFixed in
Packagist contao/core-bundle >= 4.0.0, < 5.3.50 5.3.50
Packagist contao/core-bundle >= 5.4.0-RC1, < 5.7.12 5.7.12

Details

As written in the advisory (Markdown source, shown as plain text).

`RequestTokenListener` is the only generic `REQUEST_TOKEN` validator in Contao and it only runs on POST. On the GET side the guard is local and declarative, and it only fires when an `act` parameter is present. Every back end action dispatched through a different parameter therefore has no CSRF protection at all. This is a family rather than a single bug. ### Impact An attacker who gets a logged in back end user to load a URL performs back end actions as that user, with no token and no confirmation. Because the exposure follows from the dispatch mechanism rather than from one callback, every present and future `key=` action inherits it. **Honest bound.** The victim must be authenticated in the back end and must load the URL, and the reachable actions are limited to the modules that user can access. We have not found a `key=` action that grants privileges; the ones we verified are destructive or state changing rather than escalating.

References

External links from the advisory. They lead to third-party sites.