An upload endpoint hands an attacker a way to place chosen bytes on your infrastructure, and every naive handler treats those bytes too generously: it trusts the declared type, writes under the declared name, and stores the file where the web server will happily execute it. Safe uploads verify what the bytes actually are, cap what they can consume, and store them where nothing runs.
File Upload Safety is a community-contributed Claude Code skill in the general-misc sub-category. It ships as a SKILL.md file that Claude Code auto-discovers under ~/.claude/skills/file-upload-safety/ and loads when your prompt matches the skill's trigger.
When to invoke it: Use when building an upload endpoint, an avatar or document feature, or any handler that writes client-supplied bytes to disk or object storage.
The File Upload Safety Claude Code skill is built for Claude Code users and developers across all disciplines looking for general-purpose AI assistance. It's part of ClaudSkills (also referred to as Claude Skills or Claude Code Skills) — the open community-curated registry of 196,000+ SKILL.md files for Anthropic's Claude Code agent and the wider Claude ecosystem (Claude API, Claude Agent SDK).
mkdir -p ~/.claude/skills/file-upload-safety curl -L https://claudskills.com/skills/file-upload-safety/SKILL.md \ -o ~/.claude/skills/file-upload-safety/SKILL.md
Or just download SKILL.md directly and drop it into ~/.claude/skills/file-upload-safety/. Claude Code auto-discovers it on next session.
Skills live at ~/.claude/skills/file-upload-safety/SKILL.md on macOS/Linux, or %USERPROFILE%\.claude\skills\file-upload-safety\SKILL.md on Windows. See the full install guide for step-by-step instructions.
Open @claudskills_bot on Telegram, tap Open Desktop App, and the desktop app installs this skill for you. Or share the bot link with a colleague — they get the same one-tap install. Learn more →
The ClaudSkills desktop app installs any skill directly into ~/.claude/skills/ with one click — no terminal required. Pro starts at $9/mo or $149 lifetime.
For the full experience including quality scoring and one-click install features for each skill — upgrade to Pro.
SKILL.md from the source repository to ~/.claude/skills/file-upload-safety/SKILL.md and restart Claude Code. Both flows are detailed at claudskills.com/install/.SKILL.md file that lives under ~/.claude/skills/<name>/ and tells the Claude Code CLI agent how to perform a specific task (instructions, prompts, allowed tools). Skills are auto-discovered at session start. File Upload Safety is one of 67,000+ skills indexed in the open ClaudSkills catalog, classified under the General category. Learn more at /learn/what-is-a-claude-skill/.If you reference this skill in a blog post, paper, or documentation, you can cite it as:
@misc{file-upload-safety-2026,
author = {Amey-Thakur},
title = {File Upload Safety [Claude Code skill]},
year = {2026},
publisher = {ClaudSkills},
url = {https://claudskills.com/skills/file-upload-safety/}
}Grade A · scanned 2026-09-28 — free static scan against the OWASP Agentic Skills Top 10.
The scan flagged 1 of 10 categories (filesystem), including lower-severity patterns. Patterns shown inside code fences are weighted as examples rather than instructions — read the grading methodology for what this does and does not guarantee.
Browse all General skills in the ClaudSkills registry, or explore these other picks from the same category:
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SKILL.md files, not affiliated with, endorsed by, or sponsored by Anthropic.