On their website they are using a font directly for the logo (it is not an image):
span.header-logotext-c-dark {
font-family: mirai-regular;
font-size: 40px;
color: #fff;
}
span.header-logotext-s-dark {
font-family: mirai-light;
font-size: 40px;
color: #fff;
opacity: .8;
}
That font is definitely Mirai Regular for the word "Critical" and Mirai Light for the word "stack".
UPDATE:
Fascinatingly they are apparently using a modified version in the image you provided. I'm not sure why they would represent their logo in two different ways, but, as pointed out in comments, the image version is modified significantly:

I'll leave my answer, and we'll pretend you asked what the logo on the website is! ;)
Another update after some more, let's say constructive, comments:
My best answer is that your image represents a custom typeface, very likely made by adapting Myrai.