How can a ransomware infect my computer when I visit a website? This site claims it can happen. I understand how the attachment version works but not this one. I'm a security newb.
The patch to v8: http://lpaste.net/317342
An exploit: https://gist.github.com/sroettger/d077d3907999aaa0f89d11d956...
While this bug was artificial, there were (and can still be) bugs with similar consequences in actual engines (see https://www.cvedetails.com/vulnerability-list/vendor_id-1224... or https://cve.mitre.org/cgi-bin/cvekey.cgi?keyword=spidermonke... for historical examples).
While a bug in most of the components you mention are bad by themselves, their impact is magnified by the presence of javascript, which allows an attacker to interleave calculations and interactions with the buggy components, bypassing many mitigations.