Apple has blocked the older versions of Flash player in order to protect Safari users from flaws discovered in the player.
The company has released a security update which will block older and vulnerable versions of Flash forcing users to download only the latest version of Flash content.
The new updates are aimed at addressing vulnerabilities that could cause a crash and potentially allow a hacker to take over the affected system.
Macs running OS X Mountain Lion, Lion, and Snow Leopard are affected by the change.
According to Adobe, both security flaws are being exploited in targeted attacks that try to scam Windows users into clicking on a malicious PDF file through an email. The bugs are claimed to be 'zero-day' vulnerabilities.
In February, Apple blocked the latest version of Java from running on recent versions of its Mac operating system, and blocked Java 6 from running on Mac's older versions known as Snow Leopard, due to security issues.