Lack of proper length and value checking allow attacker to cause a buffer overflow and execute arbitrary code or cause a DoS using Gecko based web browsers.
Vulnerable Systems:
* Mozilla firefox 1.0.6 and prior
* Netscape Browser version 8.0.3.3
* K-Meleon Browser version 0.9
Immune Systems:
* Mozilla firefox 1.0.7
Stack Corruption:
The problem existed in "zero-width non-joiner" sequence of unicode chars that uses Arabic shaping style. Because the code did not checked for buffer length before manipulating the given text. On a crafted content, it is possible to cause the buffer to be twice the size the actual data, and memory allocated for the buffer itself.
