>>However, in the common parlance, all sorts of things are called “viruses”.<<
Well, I used to teach debate and if you own the terms, you own the round.
So we should accept your definition because...?
It's not MY definition. The proper definitions of the terms "virus", "worm", "trojan horse", "phishing", "keylogger", and so on, have been agreed upon by the true experts in the malware field for over a decade, and you can look them up if you care to. I didn't write them.
The catch-all term "malware" covers all of the above. However, in the popular tech press, "virus" is a hot term -- gets more page hits -- so it gets used a little loosely to cover many types of malware. You referred to a Shell bug as a "virus" was so off-base it doesn't even rise to the level of being "wrong". It's in another universe, really. At first I thought you were being doubly-ironic, sort of self-satirical. But on second reading, that interpretation didn't hold.
Given your seemingly knowledgeable comments over the years on FR tech threads I assumed you were experienced, and hence would be aware of the proper terminology. If that's not true, I apologize, and will be happy to consider you just another computer user, rather than one who is familiar with the accepted technical terminology (as opposed to the tech-whore usage common in the tech press). Your call; no harm, no foul. :)
So we should accept your definition because...?
You lose.
No way is this bug a virus. Bugs are not viruses. A virus is a higher-level concept than a mere bug. It's possible to construct a virus on top of a bug, but a bug alone does not a virus make!
As to Mac OS, it's highly unlikely this bug will be the basis of a virus. That's because the population of vulnerable Macs is simply too small, due to the way Macs are typically used (as personal computers, not as servers). So, the payoff for the virus writer isn't there.
As far as Linux/Unix, the situation is much dicier. Any unpatched CGI server is vulnerable. This will attract exploits. And exploits can indeed take the form of viruses!
This means those Google engineers will hunch over their Macs and spray those patches out to their zillions of Linux servers.
How about because this is a technical issue, and a "computer virus" is a technical term with a well defined, well understood technical meaning that you obfuscated. . . thereby making the discussion far less understandable. Your usage of the word "virus" failed to communicate any accurate information. Readers were left with less information for having read what you wrote.