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- 1JWT validator skipped signature check, exposing step-by-step flaw●A JWT validator that checks every claim but never the signature tells the attacker which claim to fix next. Faav's Micro
A security writeup by Faav describes a Microsoft token validation flaw where a JWT with the 'alg:none' bypass was accepted despite failing every other check. Because the validator returned granular errors — wrong tenant, wrong audience, app allowlist rejection, then 'User not found' — it effectively guided the attacker through each requirement. The writeup also mentions an AI-driven hackbot spending ten days probing email-style attack paths.