In the CMS, the iframe renderer was not fully re-sized. The customer was populating a form inside this iframe. But since the form is bit lengthy, and iFrame was not stretching out, it is bringing a vertical scroll bar beside the renderer. The customer wished not to scroll through and the form should appear full.
The reason it was behaving this was that the inherent iframe height and width was getting applied to the content block.
Check for the respective content_block_iframe record to see what is the Sizing value is set to. In this most likely Sizing is defined as 'Expand to fit content(internal content only)'. This was applying the standard iFrame height, which is not possible to alter.
So, to resolve this, Sizing needs to be changed as 'Fixed Size' and have given an approx level of height and width so fill the page and load the details completely.