Mac users who browse the Web via Safari won't be able to access Adobe Flash-enabled sites unless they upgrade their Flash Player.
In an advisory issued Thursday, Apple said that people with out-of-date versions of Flash who try to view Flash content in Safari may see an error message such as "Blocked plug-in," "Flash Security Alert," or "Flash out-of-date," preventing them from viewing the content.
Apple has always had a contentious relationship with Adobe Flash, even going so far as to ban Flash on the iPhone and iPad. But in this case, Apple's move is designed to protect users from security threats. On Tuesday, Adobe issued a critical update for Flash Player to fix a security hole that could allow hackers to steal the cookies used to authenticate users on many popular websites. But people can be lax about updating their software, so sometimes forcing a security update is the only way to keep us from running into trouble.
Safari users who receive a message about Flash being out of date can click the Download Flash button to upgrade to the latest version. Flash users can learn more about the security update and find download links to the latest version at Adobe's Security Bulletin page for this issue.
People who use Windows, Linux, and Adobe AIR products are also urged to update their Flash Player.