s3-minio-content-type-xss

What problem does it solve?

This Skill addresses stored cross-site scripting (XSS) vulnerabilities in web applications that serve user-uploaded files from public S3 or MinIO cloud storage buckets, where attackers can override the Content-Type response header to bypass upload-time validation controls and execute malicious scripts under the target's origin.

Core Features & Use Cases

• Dual storage system support: Includes exploitation workflows for both MinIO and compatible storage systems (anonymous Content-Type override) and AWS S3 (signed presigned URL generation for overrides).
• Upload validation bypass: Provides polyglot file crafting techniques to pass extension whitelist and magic byte checks during file upload, ensuring malicious payloads reach the bucket.
• Use case: During an authorized penetration test of a social media platform that stores user avatars in a public MinIO bucket served under the platform's own domain, use this Skill to turn a benign uploaded avatar file into a same-origin stored XSS payload that steals user session cookies.

Quick Start

Use this skill to test a target's public file serving endpoint for S3 or MinIO Content-Type override vulnerabilities and generate a working same-origin stored XSS payload if the bucket is exploitable.