On September 6 a security vulnerability affecting all versions of Mozilla Firefox and the Mozilla Suite was reported to Mozilla by Tom Ferris and on September 8th was publicly disclosed.
On September 9, the Mozilla team released a configuration change which resolves this problem by explicitly disabling IDN in the browser. The fix is either a manual configuration change or a small download which will make this configuration change for the user. Instructions on administering these changes can be found below.
«Info & Installation Instructions»
Community Information
Firefox Security Patch released! 9/9/05
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After installing the patch, look to the lower taskbar for the IDN Icon.
Rightclick and uncheck IDN.

Rightclick and uncheck IDN.
Correction to above post(some info omitted)
Alternately, Install IDN Info 0.6.3 Extension
Homepage:http://4t2.cc/mozilla/idn/en
ExtensionsMirror: http://www.extensionsmirror.nl/lofiversion....php/t2668.html
Look to the lower taskbar for the IDN Icon.
Rightclick and uncheck IDN.

Alternately, Install IDN Info 0.6.3 Extension
Homepage:http://4t2.cc/mozilla/idn/en
ExtensionsMirror: http://www.extensionsmirror.nl/lofiversion....php/t2668.html
Look to the lower taskbar for the IDN Icon.
Rightclick and uncheck IDN.