medium.com/tag/bug-bounty· Sep 29, 2026· by T4nv1

$5,800 for a Negative Number: Manipulating Checkout Totals Through Business Logic Alone

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No injection. No broken authentication. No parser doing something it shouldn’t. This bug lived entirely in a spreadsheet-simple arithmetic… Continue reading on Medium »
🎯 Vulnerability: Web Security Vulnerability
💡 Defense Fix: Implement strict input validation, contextual output encoding, and enforce least-privilege authorization controls.
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