EXPL_TXTRANGE.A is a zero-day exploit that takes advantage of a vulnerability in the createTextRange Method call process in Internet Explorer. Exploiting this vulnerability enables a user to create a text range within an object. This exploit affects Internet Explorer 6.0 and Internet Explorer 7.0 Beta 2 (January Edition) running on Windows 98, ME, NT, 2000, XP, and Server 2003.
This exploit causes an error in the mentioned text range, which is applied to a an affected system's memory and to execute arbitrary codes on the system. It can also download and execute malicious codes on the system.
Zero-day exploits are termed as such because the unpatched vulnerability and its corresponding exploit code are released within the same day. This poses a threat whereby many computers may be affected due to the availability of exploit code, and the fact that vendors do not have much time to patch it.