What the vulnerability does
Description
WWBN AVideo is an open source video platform. In versions up to and including 29.0, objects/userSavePhoto.php is a legacy profile-photo endpoint that accepts a base64 POST parameter and writes the decoded bytes to videos/userPhoto/photo<users_id>.png. Its only access control is User::isLogged(). It does not end in .json.php, so it is excluded from the project's global autoCSRFGuard (which is suffix-scoped in objects/include_config.php). There is no CSRF token, no Origin/Referer check, and no MIME validation of the decoded bytes. Because AVideo's default cookie policy is SameSite=None; Secure on HTTPS (objects/functionsPHP.php:227), an attacker who lures a logged-in user to a malicious page can overwrite that user's profile photo with arbitrary bytes and also triggers a site-wide clearCache(true) on every forged request. Commit 9c38468041505e637101c5943c5370c68f48e3ac contains an updated fix.
