CVE-2026-50279

### Summary `EntriesController::actionSaveEntry()` performs entry-edit permission checks before request-controlled author changes are applied to the model. The subsequent author mutation path accepts attacker-supplied `authors` / `author` parameters and allows the change when the current user is one of the old authors. Because the controller does not re-run authorization after mutating the author list, a low-privileged user can reassign an entry’s authorship to another user without holding the dedicated peer-author-change permission. ### Details The control flow begins in [EntriesController.php](/D:/files/projects/cms-5.9.19/cms-5.9.19/src/controllers/EntriesController.php):249. `actionSaveEntry()` loads the entry and enforces edit permissions before calling `_populateEntryModel()`: ```php public function actionSaveEntry(bool $duplicate = false): ?Response { ... $entry = $this->_editableEntry($this->request->getBodyParam('entryId'), $siteId); ... $this->enforceEditEntryPermissions($entry, $duplicate); ... $this->_populateEntryModel($entry); ... $success = Craft::$app->getElements()->saveElement($entry); } ``` The attacker-controlled source is in [EntriesController.php](/D:/files/projects/cms-5.9.19/cms-5.9.19/src/controllers/EntriesController.php):588: ```php $entry->setAttributesFromRequest(array_filter([ 'authorIds' => $this->request->getBodyParam('authors') ?? $this->request->getBodyParam('author') ?? $entry->getAuthorId() ?? static::currentUser()->id, ])); ``` `Entry::setAttributesFromRequest()` in [Entry.php](/D:/files/projects/cms-5.9.19/cms-5.9.19/src/elements/Entry.php):1124 extracts the new author IDs and applies them if `canChangeAuthor()` returns true: ```php if ( ($authorIds !== null || $authorId !== null) && $this->canChangeAuthor() ) { $this->_oldAuthorIds = $oldAuthorIds; $this->setAuthorIds($authorIds); } ``` `canChangeAuthor()` at [Entry.php](/D:/files/projects/cms-5