The original title is: "A Deactivated Admin Could Still Use Their Token. That's When Dual-Mode JWT Stopped Being About Speed."

Short summary

VaultPay discovered that fast local JWT validation allowed deactivated admins to retain system access until token expiration. The fix: dual-mode validation using local checks for routine operations but strict server verification for sensitive role changes. This teaches the core tradeoff between performance and correctness in distributed microservice architectures.

• •Speed-optimized local validation missed revocation scenarios where stale permissions posed security risk
• •Deactivated admins could still authenticate because the token remained cryptographically valid
• •Solution: selective strict validation only for high-consequence operations, fast path for low-risk requests

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