How secure are QR codes?

Related questions

1. What's the difference between a QR code and a barcode?
2. When did QR codes start?
3. What is a dynamic QR code?
4. Where is my QR code on my iPhone?
5. Are there different types of QR codes?
6. What is use of QR Code?
7. Are QR codes back?
8. What information is stored in QR Code?
9. What QR code contains?
10. How were QR codes created?

Tags

1. #intent
2. #security
3. #medium
4. #however
5. #small
6. #printed
7. #there
8. #harmless
9. #billboard
10. #areas
11. #surface
12. #poster
13. #secure
14. #patterns
15. #which
16. #codes
17. #safety
18. #their
19. #digital