As far I can see, there is no Integer Validation on Image Dimension Settings, such as Avatar Dimensions, Attachment Dimensions etc. in the ACP. It is possible to enter values of the type string. This may cause problems in later usage.

Since the corresponding variables are explicitly set to false, I'm not sure, if this is a bug or the intended behaviour.

For example: acp_board.php , Line 105.

'avatar_min_height'        => false, 'avatar_min_width' => false, 'avatar_max_height' => false, 'avatar_max_width' => false,