Surfers using Firefox 3 are advised to download and install an update for the browser.
Firefox 3.0.9 brings improvements in stability and security to the browser, Mozilla said.
A bug that prevented people using AOL's webmail client and instant-messaging software, AIM, from seeing embedded images has also been fixed, the company said.
"We strongly recommend that all Firefox users upgrade to this latest release. If you already have Firefox 3, you will receive an automated update notification within 24 to 48 hours," Mozilla said in a statement.
You can also download and apply the update by selecting 'Check for updates' from the Help drop-down menu in Firefox.
An update for the Firefox 3.1 beta browser, which will soon be known as Firefox 3.5, is also expected in the next few weeks.