Mozilla issues Firefox alert

The problem is a bug rather than a flaw, the open-source browser maker insists, but still warns people about the glitch.

Colin Barker Special to CNET News
The Mozilla Foundation has issued a security advisory, acknowledging concerns about a potential flaw in its Firefox 1.5 browser.

However, the browser company strenuously denied in its Sunday advisory that the problem would cause any lasting damage to the application. It maintains that the glitch is very easy to fix.

"We have investigated this issue and can find no basis for claims that variants of this denial-of-service attack can cause an exploitable crash," Mozilla said in its advisory.

The issue came to light last Wednesday, when the first exploit code for the potential vulnerability was published.

The problem occurs with extremely long history.dat files. If the history file gets larger than 10.5MB, then the system can appear to freeze. Mozilla said the system is not actually frozen, but it takes time to clear the history buffer. The company said that to cure the problem, users need to clear the History archive.

Mozilla said in a statement that it has "issued a security advisory on a temporary start-up unresponsiveness caused by Web pages in a browser history with extremely long titles. If a user encounters this problem, the slow start can be fixed by clearing the browser history."

The problem has been given a noncritical rating by Mozilla.

Colin Barker of ZDNet UK reported from London.