hunt-http-smuggling

hunt-http-smuggling is a skill for Claude Code, Codex from adriannoes/awesome-agentic-ai. It costs 242 tokens per session (1,632 once invoked), scanned A, original, MIT.

A security testing guide for HTTP request smuggling, where a front-end proxy and back-end server disagree about where one HTTP request ends and the next begins.

In plain words
What is it for?
Use it to test Content-Length and Transfer-Encoding handling, including HTTP/2-to-HTTP/1.1 proxy setups.
Why use it?
It helps identify parsing differences that can let hidden data enter another user's request or affect shared caches.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit Use it to test Content-Length and Transfer-Encoding handling, including HTTP/2-to-HTTP/1.1 proxy setups.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/adriannoes/awesome-agentic-ai/hunt-http-smuggling
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add adriannoes/awesome-agentic-ai --skill hunt-http-smuggling
Clone the repo
git clone --depth 1 https://github.com/adriannoes/awesome-agentic-ai

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for hunt-http-smuggling

README.md
[![agentmods](https://agentmods.dev/badge/skills/adriannoes/awesome-agentic-ai/hunt-http-smuggling/github.svg)](https://agentmods.dev/skills/adriannoes/awesome-agentic-ai/hunt-http-smuggling)
Your own site
<a href="https://agentmods.dev/skills/adriannoes/awesome-agentic-ai/hunt-http-smuggling"><img src="https://agentmods.dev/badge/skills/adriannoes/awesome-agentic-ai/hunt-http-smuggling/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for hunt-http-smuggling

Your own site · 80×15
<a href="https://agentmods.dev/skills/adriannoes/awesome-agentic-ai/hunt-http-smuggling"><img src="https://agentmods.dev/badge/skills/adriannoes/awesome-agentic-ai/hunt-http-smuggling.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 242 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,632 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 1 finding. A grade says what 26 rules found in the file — not that it is safe. Third-party audits
  • NVIDIA SkillSpector pass 7 Sept 2026
How audits are shown
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00242 $0.01632
Opus 5 $0.00121 $0.00816
Sonnet 5 $0.00048 $0.00326
Haiku 4.5 $0.00024 $0.00163

Measured 7d ago against content hash 9b2bac180074, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-11, from the pricing page.

Security

Grade A, and why

hunt-http-smuggling scanned grade A with 1 finding against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 7d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

curl -sI https://target/ | grep -i "Server:"
cursor-claude-codex/skills/bug-hunter/skills/hunt-http-smuggling/SKILL.md · 82 lines

How it starts

The opening of the file, as written. The whole thing — 82 lines — stays where its author put it; the contents beside it link to each section on GitHub.

17. HTTP REQUEST SMUGGLING

Lowest dup rate. $5K–$30K. PortSwigger research by James Kettle.

CL.TE (Content-Length front, Transfer-Encoding back)

POST / HTTP/1.1
Content-Length: 13
Transfer-Encoding: chunked

0

SMUGGLED

Detection

1. Burp extension: HTTP Request Smuggler
2. Right-click request → Extensions → HTTP Request Smuggler → Smuggle probe
3. Manual timing: CL.TE probe + ~10s delay = backend waiting for rest of body

Impact Chain

Poison next request → access admin as victim
Steal credentials → capture victim's session
Cache poisoning → stored XSS at scale

Target-Suitability Matrix (2026 reality check)

The classic CL.TE / TE.CL payloads are NOT universally exploitable in 2026. Modern proxies are RFC 9112 strict by default. Fingerprint the front-end BEFORE investing time.

Front-end CL.TE TE.CL H2.CL H2.TE Notes
Nginx ≥ 1.21 NO NO partial (H2 ingress) partial RFC-strict; rejects CL+TE with HTTP 400. Verified locally on Nginx 1.27 — all 9 documented variants killed by front-end (docs/verification/phase2h-smuggling-cachepoison.md).
Caddy 2.x NO NO Hardened by default
Envoy ≥ 1.20 NO NO partial partial Hardened in most paths
HAProxy ≤ 2.4 Vulnerable, see CVE-2021-40346
AWS ALB + specific upstream partial partial Several disclosed-paid reports 2022-2024
Cloudflare → S3 / Lambda chains H2-downgrade attacks remain viable
Older F5 BIG-IP (TMM < 16) Vendor advisories
Citrix ADC / NetScaler (older firmware) Disclosed in 2020-2022
Squid 3.x Older deployments
Apache Traffic Server (older) PortSwigger research
Custom Python / Go proxies Frequently miss RFC enforcement

Read the full file on GitHub · 82 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 7d ago First seen · 82 lines · 242 tokens per session scan A 9b2bac180074

Subscribe to this mod's changes

hunt-http-smuggling is a skill published in the GitHub repository adriannoes/awesome-agentic-ai (57 stars, last pushed 13d ago), licensed MIT. It adds 242 tokens to every session and 1,632 once invoked, about $0.0012 per session on Opus 5. A static security scan graded it A with 1 finding (makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-03.

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