Executive brief
Craft CMS, a popular content management system, contains a flaw that allows certain authorized users to delete files they shouldn't have access to. Specifically, a user with permission to replace files in one area can trick the system into deleting files in a different, restricted area. This could lead to data loss, broken website links, and unauthorized removal of important digital assets.
Technical details
An authorization bypass exists in Craft CMS's `AssetsController::actionReplaceFile()` due to improper permission validation when both an `assetId` and `sourceAssetId` are provided. The controller uses a ternary expression `($assetToReplace ?: $sourceAsset)` to check permissions; when both IDs are present, it only validates the 'replace' permission for the target asset and fails to verify 'delete' permissions for the source asset. Consequently, the application copies the source file to the target and then invokes `deleteElement()` on the source asset. An authenticated attacker with file replacement privileges in any volume can exploit this to delete assets in other volumes, provided they know the target asset's ID. This issue is patched in versions 4.17.14 and 5.9.21.
Affected products
- Pixel & Tonic Craft CMS >= 4.0.0-RC1, < 4.17.14; >= 5.0.0-RC1, < 5.9.21
Timeline
- 2026-05-29: disclosed: Initial disclosure to vendor
- 2026-07-01: advisory: NVD publication date
- 2026-07-02: patched: GitHub Advisory published and versions patched
References
- https://api.github.com/users/davidbors-snyk
- https://github.com/davidbors-snyk
- https://api.github.com/users/davidbors-snyk/gists%7B/gist_id%7D
- https://api.github.com/users/davidbors-snyk/repos
- https://avatars.githubusercontent.com/u/240482518?v=4
- https://api.github.com/users/davidbors-snyk/events%7B/privacy%7D