Mozilla have claimed that the recently discovered security flaw in Firefox 1.5 is not serious. The problem, which refers to a temporary startup unresponsiveness caused by web pages in browser history with extremely long titles, has had its initially critical status questioned by Mozilla. Mozilla claims that the unresponsive starts will continue until the item with the long title is removed from the history file or eventually expires. This can happen for up to a few minutes on slower machines.

The Mozilla advisory said the issue had been investigated by its researchers and no basis had been found to back up claims that variants of this denial-of-service attack could cause an exploitable crash.

"No evidence for this claim has been offered. There does not appear to be any risk to users or their computers beyond the temporary unresponsiveness at startup," the advisory said.

There is currently no word on when a fix will be released.