Craft Cms · Craft Cms · CVE-2026-50281
**Name of the Vulnerable Software and Affected Versions**
Craft CMS versions 5.7.0 through 5.9.20
**Description**
A mass-assignment flaw exists in the bulk-duplicate element action. An attacker with permission to duplicate their own entries can overwrite other elements, such as entries, categories, or users, by submitting an arbitrary `id` through the `newAttributes` request parameter. While `ElementsController::beforeAction()` rejects `id` or `canonicalId` keys at the top level of a request, `actionBulkDuplicate()` passes the `newAttributes` array to the service layer without sufficient filtering. Specifically, `Elements::duplicateElement()` clones an element and sets its `id` to null, but `Craft::configure()` subsequently overwrites this reset with any numeric value provided in `newAttributes`. Consequently, the `saveElement()` function performs an UPDATE operation on the row matching the provided primary key instead of an INSERT, allowing the attacker to modify the title, slug, `authorId`, `postDate`, and `UID` of a victim's entry.
**Recommendations**
Update Craft CMS to version 5.9.21.