The protocol is; the implementations weren't, in this case. (To be fair, the specification didn't explicitly say "validate the origin of the pairing secret to a

The protocol is; the implementations weren't, in this case. (To be fair, the specification didn't explicitly say "validate the origin of the pairing secret to actually be a QR code scanner", but that's still more of a missing (important!) implementation warning than a protocol design flaw.) Compare this with passwords, where the protocol is fundamentally phishable, with partial mitigations requiring user discipline (e.g. only ever using password manager auto-fill) and a lack of local or remote vulnerabilities.