IMAP-Login does not work with OC 10.0.4

After upgrading from 10.0.3 to 10.0.4 ( logging in with the OC_User_IMAP- Backed does not work any more.
When enabling the following in the config.php:
"'user_backends' => array(
'class' => 'OC_User_IMAP',
'arguments' => array('{}')

the login does not work any more. After entering the credentials the following error-message occurs:
Zugriff verboten
CSRF check failed

That also occurs when trying to login with the admin-user.
When disabling the statement, the login with the admin-user works again.

The login via Owncloud-Client-Applikation does work though.

Steps to reproduce

See above

Expected behaviour

Login should work with imap

Actual behaviour

Tell us what happens instead

Server configuration

Operating system: OpenSuse

Web server: Apache2

Database: MariaDB

PHP version: 7.0

ownCloud version: (see ownCloud admin page)

Updated from an older ownCloud or fresh install: 3.0.3

Where did you install ownCloud from: tried both, admin cosole in web-view and via zip-package on console

Signing status (ownCloud 9.0 and above): ok


The content of config/config.php:

$CONFIG = array (
  'instanceid' => '***',
  'passwordsalt' => '***',
  'secret' => '***',
  'trusted_domains' =>
  array (
    0 => 'cloud.****.org',
  'datadirectory' => '/home/owncloud',
  'overwrite.cli.url' => 'https://cloud.***.org',
  'dbtype' => 'mysql',
  'version' => '',
  'dbname' => 'cloud',
  'dbhost' => 'localhost',
  'dbtableprefix' => 'oc_',
  'mysql.utf8mb4' => true,
  'dbuser' => 'cloud',
  'dbpassword' => '***',
  'logtimezone' => 'UTC',
  'installed' => true,
  'mail_from_address' => 'cloud',
  'mail_smtpmode' => 'php',
  'mail_domain' => '***.org',
  'csrf.disabled' => false,
  'user_backends' => array(
                'class' => 'OC_User_IMAP',
                'arguments' => array('{imap.***.com:993/imap/ssl}')

**List of activated apps:**

If you have access to your command line run e.g.:
sudo -u www-data php occ app:list
from within your ownCloud installation folder.

**Are you using external storage, if yes which one:no

Are you using encryption: no

Are you using an external user-backend, if yes which one: IMAP!

Client configuration

Browser: Opera

Operating system: Windows 10

Shouldn't something stopped to work after an update be reported to a bugtracker?