Updated 4/7/16: Adobe has released the 22.214.171.124 update for every browser and operating system, with the exception of Microsoft Edge on Windows 10. However, that should update automatically when the update is released.
Original story: We talk about Adobe Flash quite a bit, both because it was one of the building blocks of the modern Internet, and because in the past few years it has turned into a huge security threat. Hackers continually find weaknesses in Adobe Flash that could allow them to slip viruses onto your computer or perform a full takeover.
Adobe does update Flash monthly, and it usually releases patches at the same time as Microsoft's monthly Update Tuesday. However, sometimes Adobe has to release emergency patches early to combat serious flaws that hackers are actively exploiting. That's the case with an update coming out this week.
According to Adobe, the patch could be released "as early as April 7." It will fix a vulnerability that hackers are currently using to attack computers, both PC and Mac. If successful, the hacker can use the flaw to take over the system.
The flaw is especially bad in Flash Player versions 126.96.36.1996 and earlier. A past update, 188.8.131.52, introduced what Adobe calls a "mitigation" that makes it less likely for hackers to use the flaw. However, Adobe is still rushing out a permanent fix.
Right now you should visit this page in every browser you use to see what version of Flash it's using. If the browser isn't running the latest version of Flash you should upgrade right away to make sure you have the "mitigation" against this flaw. Then check back tomorrow to see if the update with the permanent fix is available and install that.
Note that Chrome and Microsoft Edge will update Flash automatically when new versions are available; you just need to restart the browser to get it. In fact, this author's Chrome already has Flash version 184.108.40.206 installed when Adobe says the most recent version is 220.127.116.11, so it could be the fix is arriving earlier than it predicted.
For other browsers, you'll have to manually install the Flash updates.
Alternatively, you can disable Flash in your browser or set it to only run when allowed. This will cut down your risk from attack by malicious flash ads and videos. Learn how to take control of Flash in your browser.