Iramon

If your live site is already broken, try to downgrade to 4.2.2 by downloading 4.2.2 sources and copy them to your installation directory. Before better make a backup. If that solves your problem, just wait for the bugfix to arrive. If that does not solve the problem try my hotfix from above. Open “wp-includes/kses.php” with a editor and add the above lines to kses.php line 241 between the following two lines:

),
  'ins' => array(

@denl: A possible hotfix for you would be to add the following lines of code to kses.php e.g. at line 241:

'input' => array(
      'id' => true,
      'name' => true,
      'type' => false,
      'class' => true,
      'value' => true,
    ),

But I would not recommend doing this. This adds the ‘input’ element to the list of $allowedposttags. It will work afterwords, but I have not checked, what impacts it also may have. A better solution for you would be, to stay with or upgrade to 4.2.2 and wait for a proper fix of this.

Your problem is also caused by the same code changes, which disallows using short codes in input elements. Let’s hope someone can help us.