GHSA-7h62-6v23-v8fm

## Summary

`AssetsController::actionDeleteFolder()` only requires the `deleteAssets:<volume-uid>` permission for the target folder. It never enforces `deletePeerAssets:<volume-uid>`, even though `Assets::deleteFoldersByIds()` cascades deletion to every descendant folder and every asset inside, regardless of who uploaded them. A low-privilege user who has been granted folder-management rights on a shared volume can therefore destroy assets uploaded by other users (peer assets), bypassing the per-asset peer-permission check that the sibling `actionDeleteAsset` endpoint correctly applies.

This is the same bug class that was just fixed in `actionMoveFolder` as **GHSA-3w32-23wj-rxg3** (commit `05c2042`, Apr 23 2026); the fix added `requireVolumePermissionByFolder('deletePeerAssets', …)` and `savePeerAssets` checks to the move endpoint but did not propagate to the delete-folder endpoint.

## Details

`src/controllers/AssetsController.php:552-569`:

```php public function actionDeleteFolder(): Response { $this->requireAcceptsJson(); $folderId = $this->request->getRequiredBodyParam('folderId');

$assets = Craft::$app->getAssets(); $folder = $assets->getFolderById($folderId);

if (!$folder) { throw new BadRequestHttpException('The folder cannot be found'); }

// Check if it's possible to delete objects in the target volume. $this->requireVolumePermissionByFolder('deleteAssets', $folder); // <-- only checks deleteAssets $assets->deleteFoldersByIds($folderId);

return $this->asSuccess(); } ```

`requireVolumePermissionByFolder()` (`src/controllers/AssetsControllerTrait.php:75-88`) only resolves to a single `requirePermission('deleteAssets:<vol-uid>')` call. The peer-equivalent helper (`requirePeerVolumePermissionByAsset`) is never invoked because there is no folder-level peer helper that iterates the folder's contents.

`Assets::deleteFoldersByIds()` (`src/services/Assets.php:311-349`) then enumerates the folder + every descendant folder, queries every asset under those IDs, and calls `Craft::$app->getElements()->deleteElement($asset, true)` directly:

```php $assetQuery = Asset::find()->folderId($allFolderIds); $elementService = Craft::$app->getElements();

foreach (Db::each($assetQuery) as $asset) { $asset->keepFileOnDelete = !$deleteDir; $elementService->deleteElement($asset, true); } ```

This bypasses `Asset::canDelete()` (`src/elements/Asset.php:1515-1536`):

```php public function canDelete(User $user): bool { if ($this->isFolder) { return false; } if (parent::canDelete($user)) { return true; } $volume = $this->getVolume(); if (Assets::isTempUploadFs($volume->getFs())) { return true; }

if ($this->uploaderId !== $user->id) { return $user->can("deletePeerAssets:$volume->uid"); // <-- never reached on cascade delete } return $user->can("deleteAssets:$volume->uid"); } ```

Compare to `actionDeleteAsset` (`src/controllers/AssetsController.php:579-613`), which correctly does:

```php $this->requireVolumePermissionByAsset('deleteAssets', $asset); $this->requirePeerVolumePermissionByAsset('deletePeerAssets', $asset); ```

The fix that landed in `05c2042` for `actionMoveFolder` (`src/controllers/AssetsController.php:733-765`) added both `savePeerAssets` and `deletePeerAssets` `requireVolumePermissionByFolder` checks to mirror the per-asset pattern, but the same hardening was not applied to `actionDeleteFolder` or `actionRenameFolder` (which also calls `deleteFoldersByIds` indirectly through later logic).

The asymmetry between the two endpoints demonstrates the missing check.

## Impact

- Integrity / availability of other users' assets on any volume where the attacker has `deleteAssets` but not `deletePeerAssets`: the attacker can permanently delete peer-owned files (and their parent folder structure) on the underlying filesystem, with no recovery via Craft's UI. - The Craft permission model explicitly distinguishes "delete your own assets" (`deleteAssets`) from "delete other users' assets" (`deletePeerAssets`) precisely so administrators can grant the former without the latter on shared volumes — this finding renders that distinction unenforceable for any user given folder-delete rights. - No information disclosure or remote code execution; impact is bounded to the affected volume's contents. - Does not require any non-default configuration: the affected endpoint is enabled by default and only requires that an administrator has split `deleteAssets` from `deletePeerAssets` (the documented, supported permission model).