By comparison, 85% of Firefox users were up-to-date in the same span, while only 53% Safari users could say the same.

• Safari Reader: Click on the new Reader icon to view articles on the web in a single, clutter-free page.
• Improved Performance: Safari 5 executes JavaScript up to 25% faster than Safari 4. Better page caching and DNS prefetching speed up browsing.
• Bing Search Option: New Bing search option for Safari’s Search Field, in addition to Google and Yahoo!.
• Improved HTML5 support: Safari supports over a dozen new HTML5 features, including Geolocation, full screen for HTML5 video, closed captions for HTML5 video, new sectioning elements (article, aside, footer, header, hgroup, nav and section), HTML5 AJAX History, EventSource, WebSocket, HTML5 draggable attribute, HTML5 forms validation, and HTML5 Ruby.
• Safari Developer Tools: A new Timeline Panel in the Web Inspector shows how Safari interacts with a website and identifies areas for optimization. New keyboard shortcuts make it faster to switch between panels.

Other improvements include:

• Smarter Address Field: The Smart Address Field can now match text against the titles of webpages in History and Bookmarks, as well as any part of their URL.
• Tabs Setting: Automatically open new webpages in tabs instead of in separate windows.
• Hardware Acceleration for Windows: Use the power of the computer’s graphics processor to smoothly display media and effects on PC as well as Mac.
• Search History with Date: A new date indicator in Full History Search shows when webpages were viewed.
• Top Sites/History Button: Switch easily between Top Sites and Full History Search with a new button that appears at the top of each view.
• Private Browsing Icon: A “Private” icon appears in the Smart Address Field when Private Browsing is on. Click on the icon to turn off Private Browsing.
• DNS Prefetching: Safari looks up the addresses of links on webpages and can load those pages faster.
• Improved Page Caching: Safari can add additional types of webpages to the cache so they load quickly.
• XSS Auditor: Safari can filter potentially malicious scripts used in cross-site scripting (XSS) attacks.
• Improved JavaScript Support: Safari allows web applications that use JavaScript Object Notation (JSON) to run faster and more securely.

For more information about fixes that improve performance, stability and compatibility, please see: http://support.apple.com/kb/HT4135.

For detailed information on the security content of this update, please visit this site: http://support.apple.com/kb/HT1222.

Apple has released Safari 4.0.5 to address multiple vulnerabilities in ColorSync, ImageIO, PubSub, Safari, and WebKit. These vulnerabilities may allow a remote attacker to execute arbitrary code, cause a denial-of-service condition, obtain sensitive information, or bypass security restrictions.

US-CERT encourages users and administrators to review Apple article HT4070 and upgrade to Safari 4.0.5 to help mitigate the risks.