Stop us if you've heard this one before... dozens of times. A very serious security flaw has been discovered in Adobe Flash and millions of users are impacted. The zero-day vulnerability allows hackers to exploit the flaw and crash a user's system, or even take control of the system and steal private data.

It's one of the most serious types of flaws out there and in this case the vulnerability is being actively exploited by hackers. In other words, this isn't some tiny bug discovered by researchers and handled privately with Adobe behind closed doors. Hackers are using the security hole to attack users as you read this -- and now Adobe has released an update to patch the flaw.

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Here's what you need to know: All desktop versions of Adobe Flash player are affected, including builds for Windows, OS X and Linux. So basically, if you have a computer you need to install the update.

Product Affected Versions Platform
Adobe Flash Player Desktop Runtime 21.0.0.197 and earlier Windows and Macintosh
Adobe Flash Player Extended Support Release 18.0.0.333 and earlier Windows and Macintosh
Adobe Flash Player for Google Chrome 21.0.0.197 and earlier Windows, Macintosh, Linux and ChromeOS
Adobe Flash Player for Microsoft Edge and Internet Explorer 11 21.0.0.197 and earlier Windows 10
Adobe Flash Player for Internet Explorer 11 21.0.0.197 and earlier Windows 8.1
Adobe Flash Player for Linux 11.2.202.577 and earlier Linux

How can you update? You can use the update mechanism on your computer, or you'll find direct downloads and alternative options here:

Product Updated Versions Platform Priority rating Availability
Adobe Flash Player Desktop Runtime 21.0.0.213 Windows and Macintosh 1 Flash Player Download Center

Flash Player Distribution

Adobe Flash Player Extended Support Release 18.0.0.343 Windows and Macintosh 1 Extended Support
Adobe Flash Player for Google Chrome 21.0.0.213 Windows, Macintosh, Linux and ChromeOS 1 Google Chrome Releases
Adobe Flash Player for Microsoft Edge and Internet Explorer 11 21.0.0.213 Windows 10 1 Microsoft Security Advisory
Adobe Flash Player for Internet Explorer 11 21.0.0.213 Windows 8.1 1 Microsoft Security Advisory
Adobe Flash Player for Linux 11.2.202.616 Linux 3 Flash Player Download Center