Security · 1h ago
Passwordless OTP Flaws: Inbox Boundaries Matter
Passwordless email OTP flows often fail not due to weak code generation but because delivery context is loose, allowing code reuse, race conditions, and weak audit trails. Common issues include one inbox receiving codes for multiple sessions and servers verifying codes without binding them to a specific attempt. The fix involves tying each code to a unique auth attempt ID and scoping inbox lookups to one environment per run.
Meridian48 take
This piece highlights a subtle but critical security gap that many teams overlook, emphasizing that inbox isolation is an identity concern, not just a testing one.
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