Recon Skills is a pack of security-testing skills covering reconnaissance, web applications, APIs, authentication, vulnerability validation, cloud infrastructure, and reporting. Security professionals use it for authorized assessments of systems they own or have written permission to test. The catalogue entries are individual skills from the pack.
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.
npx skills add uphiago/recon-skills --skill hunt-http-smugglinggit clone --depth 1 https://github.com/uphiago/recon-skillsWrote 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.
[](https://agentmods.dev/skills/uphiago/recon-skills/hunt-http-smuggling)<a href="https://agentmods.dev/skills/uphiago/recon-skills/hunt-http-smuggling"><img src="https://agentmods.dev/badge/skills/uphiago/recon-skills/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.
<a href="https://agentmods.dev/skills/uphiago/recon-skills/hunt-http-smuggling"><img src="https://agentmods.dev/badge/skills/uphiago/recon-skills/hunt-http-smuggling.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector warn
SkillSpector: 7 findings, up to medium
These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →
- medium Data Exfiltration · line 97 Data is being sent to an external URL. This could be legitimate telemetry or data exfiltration. Manual review is recommended.Fix: Verify the destination URL is trusted and necessary. Remove or replace with documented APIs. Ensure no secrets, tokens, or PII are transmitted.
- medium Data Exfiltration · line 203 Data is being sent to an external URL. This could be legitimate telemetry or data exfiltration. Manual review is recommended.Fix: Verify the destination URL is trusted and necessary. Remove or replace with documented APIs. Ensure no secrets, tokens, or PII are transmitted.
- medium Data Exfiltration · line 246 Data is being sent to an external URL. This could be legitimate telemetry or data exfiltration. Manual review is recommended.Fix: Verify the destination URL is trusted and necessary. Remove or replace with documented APIs. Ensure no secrets, tokens, or PII are transmitted.
- medium Data Exfiltration · line 261 Data is being sent to an external URL. This could be legitimate telemetry or data exfiltration. Manual review is recommended.Fix: Verify the destination URL is trusted and necessary. Remove or replace with documented APIs. Ensure no secrets, tokens, or PII are transmitted.
- medium Data Exfiltration · line 326 Data is being sent to an external URL. This could be legitimate telemetry or data exfiltration. Manual review is recommended.Fix: Verify the destination URL is trusted and necessary. Remove or replace with documented APIs. Ensure no secrets, tokens, or PII are transmitted.
- medium Data Exfiltration · line 328 Data is being sent to an external URL. This could be legitimate telemetry or data exfiltration. Manual review is recommended.Fix: Verify the destination URL is trusted and necessary. Remove or replace with documented APIs. Ensure no secrets, tokens, or PII are transmitted.
- medium Data Exfiltration · line 330 Data is being sent to an external URL. This could be legitimate telemetry or data exfiltration. Manual review is recommended.Fix: Verify the destination URL is trusted and necessary. Remove or replace with documented APIs. Ensure no secrets, tokens, or PII are transmitted.
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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00242 | $0.07607 |
| Opus 5 | $0.00121 | $0.03803 |
| Sonnet 5 | $0.00048 | $0.01521 |
| Haiku 4.5 | $0.00024 | $0.00761 |
Grade B, and why
hunt-http-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 8d 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.
1. Attacker hosts a page with `fetch('https://vuln-proxy/', { method: 'POST', body: '0\r\n\r\nGET /login HTTP/1.1\r\nHost: vuln-proxy\r\n\r\n', mode: 'cors' })` (or `no-cors` with `keepalive: true`) Makes network callslowCapability
Not a fault in itself. Listed so you know the mod talks to something, and to what.
curl --max-time 30 --connect-timeout 10 -sI https://target/ | grep -i "Server:" How it starts
The opening of the file, as written. The whole thing — 557 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 | Common configurations reject ambiguous CL+TE requests, but behavior still depends on the complete proxy chain. |
| 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 |
Operator fingerprint quick-check
curl --max-time 30 --connect-timeout 10 -sI https://target/ | grep -i "Server:"
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.
- 8d ago First seen · 557 lines · 242 tokens per session scan B de22afd353d8
hunt-http-smuggling is a skill published in the GitHub repository uphiago/recon-skills (1,254 stars, last pushed 10d ago), licensed MIT. It adds 242 tokens to every session and 7,607 once invoked, about $0.0012 per session on Opus 5. A static security scan graded it B with 2 findings (sends data to an external url, 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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