There is a lot of uncertainty right now about the impact of the hardware security issue named Meltdown. There will be a scheduled release of Opera which will contain a first set of workarounds as soon as the browser is properly tested and ready for release. This will most likely be at the end of January. To improve the protection it is already possible to turn on something called Strict site isolation. This separates sites into different processes which makes it harder to exploit the hardware problem.

Strict site isolation is an upcoming security feature that is still being tested. There is more information on the project page, including a list of what remains to do in the project. To turn on Strict site isolation, a user can visit opera://flags/?search=enable-site-per-process and click “Enable”.

We recommend all users to install all available operating system patches as soon as possible since this is not a problem that can be handled fully at the application level.

There is more information in the Chromium project, where Opera is developing our browser engine together with other browser vendors. See:


On 2018-01-22 Opera 50 was updated with security patches.

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  • novos7

    I have doubts about Strict Site Isolotion. This flag is designated as “highly experimental”. I’m afraid that if I turn it on I may have problems with the browser. Are my fears right? Do you know anything about the Opera’s stability problems after activating this flag?

    Is the activation of this flag very urgent?

    • The_Mocking_Turtle

      Google discovered the Spectre and Meltdown exploits and have recommended that Google Chrome users should enable said feature which is the same on Opera. I have done so on Linux Opera and noticed no ill effects whatsoever.

  • Kassandra

    I enabled this flag. But do I have to disable it again before the next Opera update or what?

  • XTide

    is it enough to apply the patch from Microsoft?? & not to apply from browsers??

  • The_Mocking_Turtle

    I switched on Opera’s “Strict Site Isolation” on a Linux laptop and noticed no difference in performance. It’s the same thing that Google recommend Chrome users to enable; both Opera and Chrome are similar “under the hood” and based on the open source browser Chromium after all.

  • andre_

    I found it’s impossible to enable Strict site isolation in Opera Developer (ver.51), both on Win 10 and Mac. However, the same main version on Opera Beta allows the flag to be enabled.
    Is it a feature, or there’s something wrong with both my installations?
    Opera Developer was my primary browser on Windows…