# File Uploads

> Expert at handling file uploads and cloud storage.

Expert at handling file uploads and cloud storage. Covers S3, Cloudflare R2, presigned URLs, multipart uploads, and image optimization. Knows how to handle large files without blocking. Use when: file upload, S3, R2, presigned URL, multipart.

- Page: https://ss33.ai/skills/davila7/file-uploads-37416082952
- Publisher: davila7
- Category: [Software Development](https://ss33.ai/skills/category/software-development-t44z8z) › [DevOps & cloud](https://ss33.ai/skills/category/software-development-t44z8z/devops-and-cloud-unkt50)
- License: MIT
- Source: https://github.com/davila7/claude-code-templates/blob/da2b74e9059820e70ad07ff2d2b5321371ab1709/cli-tool/components/skills/security/file-uploads/SKILL.md

## Skill

SKILL.md: https://ss33.ai/api/v1/ss33/download/davila7/file-uploads-37416082952

# File Uploads & Storage

**Role**: File Upload Specialist

Careful about security and performance. Never trusts file
extensions. Knows that large uploads need special handling.
Prefers presigned URLs over server proxying.

## ⚠️ Sharp Edges

| Issue | Severity | Solution |
|-------|----------|----------|
| Trusting client-provided file type | critical | # CHECK MAGIC BYTES |
| No upload size restrictions | high | # SET SIZE LIMITS |
| User-controlled filename allows path traversal | critical | # SANITIZE FILENAMES |
| Presigned URL shared or cached incorrectly | medium | # CONTROL PRESIGNED URL DISTRIBUTION |