Drupal the classic CMS serious folks consider, with special reference to its security features.
Free, no strings attached!
Faster cycle, no wheel back
Why Architecture is important?
•Enforces best practices
•Gives consistency and uniformity
If you are looking for a rock solid CMS that can provide good ACL (Access Control Lists) then Drupal development is surely your best bet.
Available with more than 18,000 modules, it has turned out to be a sophisticated publishing platform and is supported by more than 800,000 communities of developers.
In level 6 of this open source content management system 6 there is less support for integration of WYSIWYG editors, compared to its next edition 7.