{"id":"GHSA-7jx7-3846-m7w7","summary":"Craft CMS Vulnerable to potential authenticated Remote Code Execution via malicious attached Behavior","details":"## Relationship to Previously Patched Vulnerability\n\nThis vulnerability is **in addition to** the RCE vulnerability patched in [GHSA-255j-qw47-wjh5](https://github.com/craftcms/cms/security/advisories/GHSA-255j-qw47-wjh5). That advisory addressed a similar RCE vulnerability that affected two specific routes:\n\n- `/index.php?p=admin%2Factions%2Ffields%2Fapply-layout-element-settings`\n- `/index.php?p=admin%2Factions%2Ffields%2Frender-card-preview`\n\nThis one addresses some additional endpoints that were not covered in the https://github.com/craftcms/cms/security/advisories/GHSA-255j-qw47-wjh5.\n\nThe patched vulnerability used a malicious `AttributeTypecastBehavior` with a wildcard event listener (`\"on *\": \"self::beforeSave\"`) and `__construct()` syntax to trigger RCE via the `typecastBeforeSave` callback. The fix was implemented in commits:\n- [6e608a1](https://github.com/craftcms/cms/commit/6e608a1a5bfb36943f94f584b7548ca542a86fef)\n- [27f5588](https://github.com/craftcms/cms/commit/27f55886098b56c00ddc53b69239c9c9192252c7)\n- [ec43c49](https://github.com/craftcms/cms/commit/ec43c497edde0b2bf2e39a119cded2e55f9fe593)\n\nThis vulnerability follows the same attack pattern (behavior injection via `\"as \u003cbehavior\u003e\"` syntax) but affects a **different code path** (`assembleLayoutFromPost()` in `Fields.php`) that was **not patched** in those commits. The attack vector uses `typecastAfterValidate` instead of `typecastBeforeSave` and does not require the wildcard event listener syntax, demonstrating that multiple entry points exist for this type of vulnerability.\n\n---\n\n## Executive Summary\n\nA Remote Code Execution (RCE) vulnerability exists in Craft CMS where the `assembleLayoutFromPost()` function in `src/services/Fields.php` fails to sanitize user-supplied configuration data before passing it to `Craft::createObject()`. This allows authenticated administrators to inject malicious Yii2 behavior configurations that execute arbitrary system commands on the server. This vulnerability represents an **unpatched variant** of the behavior injection vulnerability addressed in GHSA-255j-qw47-wjh5, affecting different endpoints through a separate code path.\n\n---\n\n## Vulnerability Details\n\n### Attack Prerequisites\n\n- **Authentication:** Admin-level access required\n- **Network Access:** Access to admin panel (`/admin`)\n\n---\n\n\n### Location\n\n- **File:** `src/services/Fields.php`\n- **Function:** `assembleLayoutFromPost()` (lines 1125-1143)\n- **Root Cause:** Missing `cleanseConfig()` call on user-supplied `fieldLayout` POST parameter\n\n### Vulnerable Code Path\n\n```php\n// src/services/Fields.php:1125-1133\npublic function assembleLayoutFromPost(?string $namespace = null): FieldLayout\n{\n    $paramPrefix = $namespace ? rtrim($namespace, '.') . '.' : '';\n    $request = Craft::$app-\u003egetRequest();\n    $config = JsonHelper::decode($request-\u003egetBodyParam(\"{$paramPrefix}fieldLayout\"));\n    // ... additional config values added ...\n    $layout = $this-\u003ecreateLayout($config);  // \u003c-- No cleanseConfig() call!\n    // ...\n}\n\n// src/services/Fields.php:1089-1093\npublic function createLayout(array $config): FieldLayout\n{\n    $config['class'] = FieldLayout::class;\n    return Craft::createObject($config);  // \u003c-- Untrusted data passed directly\n}\n```\n---\n\n## Attack Chain\n\nThe exploitation leverages Yii2's object configuration system and behavior attachment mechanism:\n\n1. **Behavior Injection:** Attacker includes `'as rce'` key in the `fieldLayout` JSON POST parameter\n2. **Object Creation:** `Craft::createObject()` processes the config through Yii2's `BaseYii::configure()`\n3. **Behavior Attachment:** Yii2's `Component::__set()` detects the `'as '` prefix and attaches the behavior\n4. **RCE Trigger:** When `validate()` is called on the model, `EVENT_AFTER_VALIDATE` fires\n5. **Command Execution:** `AttributeTypecastBehavior` calls the configured typecast function (`ConsoleProcessus::execute`) with the `uid` attribute value as the command\n\n### RCE Gadget Chain\n\n```\nFieldLayout POST parameter\n    → Craft::createObject()\n    → Yii2 Component::__set() with 'as rce' key\n    → AttributeTypecastBehavior attached\n    → Model::validate() called\n    → EVENT_AFTER_VALIDATE triggered\n    → typecastAfterValidate → typecastAttributes()\n    → call_user_func(['Psy\\Readline\\Hoa\\ConsoleProcessus', 'execute'], $command)\n    → Shell command execution\n```\n\n---\n\n## Affected Controllers\n\nThe `assembleLayoutFromPost()` function is called by multiple admin controllers:\n\n| Controller | Action | Permission Required |\n|------------|--------|---------------------|\n| `TagsController` | `actionSaveTagGroup()` | Admin |\n| `CategoriesController` | `actionSaveGroup()` | Admin |\n| `EntryTypesController` | `actionSave()` | Admin |\n| `GlobalsController` | `actionSaveSet()` | Admin |\n| `VolumesController` | `actionSave()` | Admin |\n| `UsersController` | `actionSaveUserFieldLayout()` | Admin |\n| `AddressesController` | `actionSaveAddressFieldLayout()` | Admin |\n\n---\n## References\n\n- https://github.com/craftcms/cms/commit/395c64f0b80b507be1c862a2ec942eaacb353748\n- [GHSA-255j-qw47-wjh5](https://github.com/craftcms/cms/security/advisories/GHSA-255j-qw47-wjh5) - Previously patched RCE vulnerability via behavior injection (affecting different endpoints)\n- [CVE-2024-4990](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2024-4990) - Related vulnerability that inspired the behavior injection attack pattern\n- [Yii2 GHSA-gcmh-9pjj-7fp4](https://github.com/yiisoft/yii2/security/advisories/GHSA-gcmh-9pjj-7fp4) - Original Yii framework report (framework team declined to fix at framework level)\n\n---","aliases":["CVE-2026-25498"],"modified":"2026-04-02T13:29:24.688478228Z","published":"2026-02-09T20:36:43Z","related":["CVE-2026-32263","CVE-2026-32264"],"database_specific":{"nvd_published_at":"2026-02-09T20:15:58Z","cwe_ids":["CWE-470"],"severity":"HIGH","github_reviewed":true,"github_reviewed_at":"2026-02-09T20:36:43Z"},"references":[{"type":"WEB","url":"https://github.com/craftcms/cms/security/advisories/GHSA-7jx7-3846-m7w7"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-25498"},{"type":"WEB","url":"https://github.com/craftcms/cms/commit/395c64f0b80b507be1c862a2ec942eaacb353748"},{"type":"PACKAGE","url":"https://github.com/craftcms/cms"},{"type":"WEB","url":"https://github.com/craftcms/cms/releases/tag/4.16.18"},{"type":"WEB","url":"https://github.com/craftcms/cms/releases/tag/5.8.22"}],"affected":[{"package":{"name":"craftcms/cms","ecosystem":"Packagist","purl":"pkg:composer/craftcms/cms"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"5.0.0-RC1"},{"fixed":"5.8.22"}]}],"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","5.8.3","5.8.4","5.8.5","5.8.6","5.8.7","5.8.8","5.8.9"],"database_specific":{"last_known_affected_version_range":"\u003c= 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