CORS Misconfiguration: The Open Door You Didn't Know About

Sat, 14 Feb 2026 00:00:00 +0000

CORS misconfiguration is one of those vulnerabilities that keeps coming up because most developers don’t fully understand what CORS actually does. It’s the browser mechanism that controls which websites can make requests to your API. When it’s configured correctly, it prevents malicious sites from stealing data through a victim’s browser. When it’s misconfigured, and this happens constantly based on public bug bounty reports, it effectively disables the Same-Origin Policy, letting any website read authenticated responses from your API. What makes CORS misconfigurations particularly interesting to study is that they’re invisible to users, silent in server logs, and trivial to exploit.

CWE-346 on guy@secdev.uk

CORS Misconfiguration: The Open Door You Didn't Know About