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One of the biggest misconceptions in application security is that Broken Access Control only exists around admin panels or sensitive endpoints.

In reality, some of the most impactful vulnerabilities begin in places almost nobody pays attention to.

During one of my recent security assessments on target.com, I was exploring what looked like a completely ordinary account settings page. Like most profile pages, it allowed users to update their personal information and preferences. Nothing about it immediately suggested that it could lead to a security issue.

As I spent more time understanding how the application handled profile updates, that seemingly harmless feature turned into a cross-tenant Broken Access Control vulnerability that allowed an authenticated user to associate their account with other organizations and disclose sensitive metadata belonging to completely different customers.

The report was acknowledged by the security team within just six hours of submission, but more importantly, it reinforced another lesson I’ve learned repeatedly throughout bug hunting:

Sometimes the most dangerous vulnerabilities are hiding inside the features users interact with every day.