# HTTP Request Smuggling

> Detects HTTP response headers and server configurations vulnerable to request smuggling via Transfer-Encoding/Content-Length discrepancies.

- Skill: `zakirkun/http-request-smuggling` (Agent Skill, multi-file: 2 files)
- Install (CLI): `npx skillmds@latest add zakirkun/http-request-smuggling`
- Raw SKILL.md: https://api.skillmd.com/api/skills/zakirkun/http-request-smuggling/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: zakirkun (https://skillmd.com/u/zakirkun)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/zakirkun/http-request-smuggling

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# HTTP Request Smuggling

## Overview
HTTP Request Smuggling exploits discrepancies in how front-end (proxy/CDN) and back-end servers parse HTTP request boundaries. By crafting requests with ambiguous `Content-Length` and `Transfer-Encoding` headers, attackers can:
- Bypass security controls at the proxy layer
- Poison the request queue affecting other users
- Achieve XSS, redirect stealing, and cache poisoning

## Detection Strategy
Look for custom HTTP header handling that processes both Content-Length and Transfer-Encoding, or proxy configurations that forward headers without normalization.

## Remediation
- Use HTTP/2 end-to-end where possible
- Normalize HTTP headers at the proxy layer
- Configure backend to reject ambiguous requests