This is a big issue and broke a lot of our websites unfortunately.
The problem is that the cdata_handler will be called when the parser finds tokens like < and passes nothing to your cdata_handler which it’s suppose to pass things like < or >.
The problem is with libxml 2.7.0 and 2.7.1 and 2.7.2 fixes the issue:
http://xmlsoft.org/news.html
They say 2.7.2 fixes it but it doesn’t really, it’s very disappointing.
Hamid Alipour is a partner in Codehead, LLP with his wife, Tess. Hamid speaks 12 markup and programming languages [Yes, 12: PHP, CSS, Ajax, JavaScript, HTML/XHTML, Java, Python, C/C++, ASP, Visual Basic, Scheme and Action Script]; has a penchant for solving the unsolvable; an affinity for clean, hand-written code and is a Zend Certified 