{"id":"GHSA-qq2c-2q8j-jh27","aliases":["CVE-2026-50279"],"title":"Craft CMS: Authorship spoofing in `entries/save-entry` via pre-check/post-mutation authorization gap","titleSource":"OSV","descriptionSource":"OSV","declaredSeverity":"HIGH","description":"### Summary\n\n`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.\n\n### Details\nThe 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()`:\n\n```php\npublic function actionSaveEntry(bool $duplicate = false): ?Response\n{\n    ...\n    $entry = $this->_editableEntry($this->request->getBodyParam('entryId'), $siteId);\n    ...\n    $this->enforceEditEntryPermissions($entry, $duplicate);\n    ...\n    $this->_populateEntryModel($entry);\n    ...\n    $success = Craft::$app->getElements()->saveElement($entry);\n}\n```\n\nThe attacker-controlled source is in [EntriesController.php](/D:/files/projects/cms-5.9.19/cms-5.9.19/src/controllers/EntriesController.php):588:\n\n```php\n$entry->setAttributesFromRequest(array_filter([\n    'authorIds' => $this->request->getBodyParam('authors') ??\n        $this->request->getBodyParam('author') ??\n        $entry->getAuthorId() ??\n        static::currentUser()->id,\n]));\n```\n\n`Entry::setAttributesFromRequest()` in [Entry.php](/D:/files/projects/cms-5.9.19/cms-5.9.19/src/elements/Entry.php):1124 extracts the new author IDs and applies them if `canChangeAuthor()` returns true:\n\n```php\nif (\n    ($authorIds !== null || $authorId !== null) &&\n    $this->canChangeAuthor()\n) {\n    $this->_oldAuthorIds = $oldAuthorIds;\n    $this->setAuthorIds($authorIds);\n}\n```\n\n`canChangeAuthor()` at [Entry.php](/D:/files/projects/cms-5.9.19/cms-5.9.19/src/elements/Entry.php):2789 allows the author change when the current user can view peer entries and is already one of the existing authors:\n\n```php\nreturn (\n    empty($authorIds) ||\n    in_array($user->id, $authorIds) ||\n    $user->can(\"changeAuthorForPeerEntries:$section->uid\")\n);\n```\n\nAfter the author list is mutated, the controller does not re-check authorization. \n\nThis closes the exploit chain:\n\n1. External source: authenticated request to `entries/save-entry` with attacker-controlled `authors[]`.\n2. Trust boundary failure: authorization is checked on the pre-mutation entry state, not on the post-mutation author assignment.\n3. Privileged sink: the author relationship is rewritten in persistent storage.\n\nPreconditions derived from the source:\n\n1. The attacker is authenticated and can edit entry `345`.\n2. The attacker is among the existing authors of entry `345`, or otherwise satisfies `canChangeAuthor()` through the old author set.\n3. The attacker has `viewPeerEntries` for the section.\n4. User ID `1` exists and can be assigned as an author in that section.\n\nResult:\n\n1. `enforceEditEntryPermissions()` succeeds on the original entry state.\n2. `_populateEntryModel()` reads `authors[]=1` from the request body.\n3. `setAttributesFromRequest()` updates `authorIds` because `canChangeAuthor()` is evaluated against the old authorship state.\n4. `saveElement()` persists the change and `_saveAuthors()` rewrites the entry-author relation.\n5. Entry `345` now appears authored by user `1`.\n\n### Impact\n\nThis allows low-privileged users to falsify content ownership and alter the authorship of entries without having the dedicated author-management permission. The impact includes corrupted audit trails, misleading notifications, broken approval workflows, and unauthorized reassignment of content responsibility.","severity":"high","score":7.6,"published":"2026-07-02T18:45:28.000Z","modified":"2026-09-10T03:50:52.940Z","withdrawn":false,"knownExploited":false,"affected":[{"ecosystem":"Packagist","name":"craftcms/cms","sources":[{"name":"OSV · GHSA-qq2c-2q8j-jh27","url":"https://osv.dev/vulnerability/GHSA-qq2c-2q8j-jh27"}],"ranges":[{"events":[{"introduced":"5.0.0-RC1"},{"fixed":"5.9.21"}],"type":"ECOSYSTEM"}],"versions":["5.0.0","5.0.0-RC1","5.0.1","5.0.2","5.0.3","5.0.4","5.0.5","5.0.6","5.1.0","5.1.1","5.1.10","5.1.2","5.1.3","5.1.4","5.1.5","5.1.6","5.1.7","5.1.8","5.1.9","5.2.0","5.2.0-beta.1","5.2.0-beta.2","5.2.0-beta.3","5.2.0-beta.4","5.2.0-beta.5","5.2.0-beta.6","5.2.1","5.2.10","5.2.2","5.2.3","5.2.4","5.2.4.1","5.2.5","5.2.6","5.2.7","5.2.8","5.2.9","5.3.0","5.3.0-beta.1","5.3.0-beta.2","5.3.0.1","5.3.0.2","5.3.0.3","5.3.1","5.3.2","5.3.3","5.3.4","5.3.5","5.3.6","5.4.0","5.4.0.1","5.4.1","5.4.10","5.4.10.1","5.4.2","5.4.3","5.4.4","5.4.5","5.4.5.1","5.4.6","5.4.7","5.4.7.1","5.4.8","5.4.9","5.5.0","5.5.0.1","5.5.1","5.5.1.1","5.5.10","5.5.2","5.5.3","5.5.4","5.5.5","5.5.6","5.5.6.1","5.5.7","5.5.8","5.5.9","5.6.0","5.6.0.1","5.6.0.2","5.6.1","5.6.10","5.6.10.1","5.6.10.2","5.6.11","5.6.12","5.6.13","5.6.14","5.6.15","5.6.16","5.6.17","5.6.2","5.6.3","5.6.4","5.6.5","5.6.5.1","5.6.6","5.6.7","5.6.8","5.6.9","5.6.9.1","5.7.0","5.7.0-beta.1","5.7.0-beta.2","5.7.1","5.7.1.1","5.7.10","5.7.11","5.7.2","5.7.3","5.7.4","5.7.5","5.7.6","5.7.7","5.7.8","5.7.8.1","5.7.8.2","5.7.9","5.8.0","5.8.1","5.8.10","5.8.11","5.8.12","5.8.13","5.8.13.1","5.8.13.2","5.8.14","5.8.15","5.8.16","5.8.17","5.8.18","5.8.19","5.8.2","5.8.20","5.8.21","5.8.22","5.8.23","5.8.3","5.8.4","5.8.5","5.8.6","5.8.7","5.8.8","5.8.9","5.9.0","5.9.0-beta.1","5.9.0-beta.2","5.9.1","5.9.10","5.9.11","5.9.12","5.9.13","5.9.14","5.9.15","5.9.16","5.9.17","5.9.18","5.9.19","5.9.2","5.9.20","5.9.3","5.9.4","5.9.5","5.9.6","5.9.7","5.9.8","5.9.9"],"fixed":["5.9.21"]}],"sourceAffected":[],"references":["https://github.com/craftcms/cms/security/advisories/GHSA-qq2c-2q8j-jh27","https://nvd.nist.gov/vuln/detail/CVE-2026-50279","https://github.com/craftcms/cms/commit/9cc493be8b414d7116c7f2bc2a6d0926e73f1248","https://github.com/craftcms/cms"],"sources":[{"name":"OSV","id":"GHSA-qq2c-2q8j-jh27","modified":"2026-09-10T03:50:52.940581232Z","url":"https://osv.dev/vulnerability/GHSA-qq2c-2q8j-jh27"}],"assessments":[{"source":"OSV","vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N","score":7.6}],"products":[],"remediation":[],"kev":{"status":"not-listed","checkedAt":"2026-10-28T16:00:31.263Z"},"coverage":[{"source":"NVD","status":"not-checked"},{"source":"GHSA","status":"not-checked"},{"source":"EUVD","status":"not-checked"},{"source":"EPSS","status":"not-checked"}],"evidence":[]}