GreyMagic Software reported that the problem affects XMLHttpRequest, which allows Web pages in the browser to send and receive XML data via HTTP, the standard Web transfer protocol. XML is an Internet language for describing just about any sort of data.
The bug is found in versions of Mozilla from 0.9.7 to 0.9.9 on various operating system platforms, and in Netscape versions 6.1 and higher. The flaw doesn't affect Mozilla 1.0 release candidate 1 because XMLHttpRequest appears to be broken in that release, according to Mozilla developers.
Source: zdnet.com