smuggling

smuggling is a skill for Claude Code, Codex from MingyiSecLab/Mingyi-Atlas. It costs 97 tokens per session (9,617 once invoked), scanned B, a copy of smuggling, Apache-2.0.

A security testing guide for HTTP request smuggling, where a proxy and a back-end server disagree about where requests end. It covers ways to confirm and exploit this mismatch across common HTTP versions and connection setups.

In plain words
What is it for?
It is for testing proxies, CDNs, and origin servers for desynchronisation, including request-boundary checks, header variations, HTTP/2 downgrades, and raw-socket test scripts.
Why use it?
It helps investigate cases where front-end checks can be bypassed because the back-end interprets a request differently. This can expose other users' requests or reach protected routes.

Skill for Claude CodeCodex

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

Good fit It is for testing proxies, CDNs, and origin servers for desynchronisation, including request-boundary checks, header variations, HTTP/2 downgrades, and raw-socket test scripts.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/mingyiseclab/mingyi-atlas/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 MingyiSecLab/Mingyi-Atlas --skill smuggling
Clone the repo
git clone --depth 1 https://github.com/MingyiSecLab/Mingyi-Atlas

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 smuggling

README.md
[![agentmods](https://agentmods.dev/badge/skills/mingyiseclab/mingyi-atlas/smuggling/github.svg)](https://agentmods.dev/skills/mingyiseclab/mingyi-atlas/smuggling)
Your own site
<a href="https://agentmods.dev/skills/mingyiseclab/mingyi-atlas/smuggling"><img src="https://agentmods.dev/badge/skills/mingyiseclab/mingyi-atlas/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 smuggling

Your own site · 80×15
<a href="https://agentmods.dev/skills/mingyiseclab/mingyi-atlas/smuggling"><img src="https://agentmods.dev/badge/skills/mingyiseclab/mingyi-atlas/smuggling.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 97 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 9,617 The whole file, excluding the scripts and references it only reads on demand.
Security scan B 2 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin 95% copy Near-identical to another mod 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 $0.00097 $0.09617
Opus 5 $0.00048 $0.04809
Sonnet 5 $0.00019 $0.01923
Haiku 4.5 $0.00010 $0.00962

Measured 9d ago against content hash 6c44ac381f5c, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-12, from the pricing page.

Security

Grade B, and why

smuggling scanned grade B with 2 findings 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 9d 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.

Sends data to an external URLmediumData exfiltration

A POST to an outside endpoint may be telemetry or may be exfiltration; either way the mod talks to somewhere, and you should know where.

curl -s -i -c cookies.txt -d "username=$LOW_USER&password=$LOW_PASS" "$TARGET/<login_path>" | tee login.txt

Makes network callslowCapability

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

| 1 | `curl -sv <TARGET>/` 2>&1 \| grep -iE '^(server\|via\|x-)' | First-line tier (front-most CDN/WAF/MITM banner) |
Origin

This is a copy

95% identical to smuggling — 3 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

src/skills/standard/exploit/web/smuggling/SKILL.md · 656 lines

How it starts

The opening of the file, as written. The whole thing — 656 lines — stays where its author put it; the contents beside it link to each section on GitHub.

HTTP Request Smuggling (Desync)

Exploits parser disagreement between two HTTP intermediaries on the same connection (front-end CDN/proxy ↔ back-end origin). When one side ends a request at byte X and the other at byte Y, the bytes between X and Y are the "smuggled" prefix of the next victim request — letting the attacker rewrite the next user's request, steal cookies/headers, or hit auth-bypassed routes.

When This Skill Is Primary

HRS bypasses authentication and authorization at the front-end/back-end boundary — it does NOT need correct credentials. When smuggling_desync (or request_smuggling / hrs / desync) co-occurs with credential-related tags (default_credentials, jwt, weak_password), smuggling IS the primary attack vector. Credential brute-force is a fallback only after the confirm-desync gate (below) fires NEGATIVE.

Reasoning: a CTF that ships both tags is signaling "you have a low-priv account (test:test, etc.) — use it as your session anchor and bypass the role check via parser disagreement." Burning the time budget on admin:* brute-force misses the design entirely. Use the low-priv credentials as the OUTER request session; smuggle the privileged INNER request.

The same logic applies when smuggling_desync co-occurs with cve (the CVE is likely the desync primitive; e.g., CVE-2022-24766 is mitmproxy h1 smuggling — see Variant Catalog → CL.0 / pause-based desync below).

Recognition Signals

Trigger this skill when ANY of the following are present:

  • Multi-proxy stack visible: two Server: strings across responses (e.g. cloudflare then gunicorn); Via: header present; CDN/edge fingerprint (Cloudflare CF-RAY, AWS CloudFront, Akamai, Fastly).
  • Differential 400/501 when sending duplicate/obfuscated Transfer-Encoding or Content-Length headers (one path 200, another 400/501).
  • HTTP/2 frontend with HTTP/1.1 backend (alt-svc: h2, :status pseudo-header, HTTP/2 ALPN). Downgrades are the modern smuggling surface.
  • Pipelining differences: connection reused across requests with inconsistent framing.
  • Challenge tag includes smuggling_desync, request_smuggling, hrs, desync, or recon's "Frontend behavior" line says "frontend forwards malformed framing".
  • Recon handoff notes that the same payload yields different status codes when sent to different proxy hops or with different framing.

Read the full file on GitHub · 656 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. 9d ago First seen · 656 lines · 97 tokens per session scan B 6c44ac381f5c

Subscribe to this mod's changes

smuggling is a skill published in the GitHub repository MingyiSecLab/Mingyi-Atlas (11 stars, last pushed 2mo ago), licensed Apache-2.0. It adds 97 tokens to every session and 9,617 once invoked, about $0.0005 per session on Opus 5. A static security scan graded it B with 2 findings (sends data to an external url, makes network calls). It is 95% identical to smuggling, differing in 3 lines, and is treated as a copy.