HackSkills is an organized knowledge base of installable skills that gives AI agents practical security knowledge across areas such as web security, privilege escalation, reverse engineering, and digital forensics. It is intended for bug bounty work, penetration testing, CTF competitions, and authorized security research. The catalogue entries are the project's own master, category, and topic skills.
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 yaklang/hack-skills --skill request-smugglinggit clone --depth 1 https://github.com/yaklang/hack-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/yaklang/hack-skills/request-smuggling)<a href="https://agentmods.dev/skills/yaklang/hack-skills/request-smuggling"><img src="https://agentmods.dev/badge/skills/yaklang/hack-skills/request-smuggling.svg" alt="Measured on agentmods" height="20"></a>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 | $0.00062 | $0.03178 |
| Opus 5 | $0.00031 | $0.01589 |
| Sonnet 5 | $0.00012 | $0.00636 |
| Haiku 4.5 | $0.00006 | $0.00318 |
Grade B, and why
request-smuggling scanned grade B 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 3d 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.
fetch("https://target.example/vulnerable", { method: "POST", Copies of this mod
3 near-identical copies found in the catalogue:
- request-smuggling — 100% identical, 7 lines differ
- request-smuggling — 100% identical, 0 lines differ
- request-smuggling — 98% identical, 2 lines differ
How it starts
The opening of the file, as written. The whole thing — 315 lines — stays where its author put it; the contents beside it link to each section on GitHub.
SKILL: HTTP Request Smuggling — Expert Attack Playbook
AI LOAD INSTRUCTION: Expert HTTP desync techniques. Covers CL.TE, TE.CL, TE.TE obfuscation variants, HTTP/2 downgrade and pseudo-header confusion, client-side desync (browser
fetchpipelines), and tool-assisted fuzzing. Assumes familiarity with raw HTTP/1.1 framing and reverse-proxy topologies. This is not “header injection” — it is message boundary disagreement between hops.
Routing note: load this skill when you suspect CDN/reverse-proxy and origin disagree on request-end boundaries, or when abnormal concatenation appears during H2-to-H1 downgrade.
0. RELATED ROUTING
- ghost-bits-cast-attack when the HTTP client library is Apache HttpClient <= 4.5.9 (HTTPCLIENT-1974/1978) — injecting
瘍瘊(U+760D U+760A, low bytes\r\n) into a header value causes the underlying char-to-byte writer to emit a literal CRLF, splitting the request at the origin without relying on CL/TE disagreement
1. QUICK START
CL.TE first probe (front-end trusts CL, back-end trusts chunked)
Assumption: front end prioritizes Content-Length, back end prioritizes Transfer-Encoding: chunked. Use a very short CL so the front end accepts a fake end, while the back end continues chunk parsing and leaves remaining bytes for the next request.
POST / HTTP/1.1
Host: target.example
Content-Type: application/x-www-form-urlencoded
Content-Length: 13
Transfer-Encoding: chunked
0
SMUGGLED
- Front end reads only 13 bytes based on
Content-Length: 13(that is,0\r\n\r\nSMUGGLED, 13 bytes total) and considers the request complete. - Back end parses as chunked: after the
0end chunk, it treatsSMUGGLEDand onward as the start byte stream of the next request.
TE.CL first probe (front-end trusts chunked, back-end trusts CL)
Assumption: front end parses chunked and back end only reads Content-Length. Set CL equal to the number of bytes in the chunk-length line (commonly 4: two hex characters + \r\n), so the back end consumes only the length line and leaves the rest buffered for follow-up request splicing.
What ships with it
1 file beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
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.
- 3d ago First seen · 315 lines · 62 tokens per session scan B 6469b8e00d95
request-smuggling is a skill published in the GitHub repository yaklang/hack-skills (2,098 stars, last pushed 2mo ago), licensed MIT. It adds 62 tokens to every session and 3,178 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it B with 1 finding (sends data to an external url). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-03.
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