sure, but visiting any website or launching any app has those vulnerabilities too, except they're many times more complicated. even if it's a legit site, they could have been hacked, best to just not touch external data ever if that's your threat model.

This has actually happened before. [0]

> An exploitable code execution vulnerability exists in the QR code scanning functionality of Yi Home Camera 27US 1.8.7.0D. A specially crafted QR Code can cause a buffer overflow, resulting in code execution.

[0] https://talosintelligence.com/vulnerability_reports/TALOS-20...

Note that it was not in the QR scanner itself -- the parsing part was fine, the image was always decoded safely. It is the network setup script which parsed the extracted text which was vulnerable.

And this is not unique to QR codes -- the correct setup string looked like "b=USmtPf6GnLZYDuR9&s=PCheX14pPg==&p=AbCD123465". This already looks like gibberish to most people; if this was replaced with evil string, I am not sure user would realize that.

Uh, no? At least in mobile OS's, the applications are isolated very strongly. And QR reader app is likely to have minimal permissions, and does not declare "backgroup daemon" one -- so even if app is entirely taken over, the worst it can do is to show scary messages and redirect you to nasty URL.

The former is easily ignorable, while the latter is no worse than typing random link shortener URL you found on paper.

Imagine if someone discovers a flaw in any library that your web browser uses, or the browser itself or is JS engine ... oh no!