Overview
MIME Type Filter Bypass focuses on an upload feature that relies on the submitted MIME type to decide whether a file is safe.
This lab shows why client-provided metadata is not a reliable security boundary. Content type headers can be inaccurate, manipulated, or disconnected from how the server later stores and serves the file.
Security Impact
Trusting MIME type alone can allow unsafe files into application storage. If those files are later served from a trusted domain or processed by backend components, the impact can include content spoofing, stored client-side attacks, or server-side execution risk.
Vulnerability Scope
Image uploaders, document portals, media libraries, and attachment workflows are exposed when the server trusts HTTP headers more than the actual file content and storage policy.
Lab Focus
The lab focuses on MIME-based upload controls, why validation must happen server-side, and how content inspection, extension policy, and execution isolation work together.
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