http-connection-contamination SKILL.md skillA
http-connection-contamination from dreadnode/capabilities is an agent skill: a SKILL.md folder an AI agent loads when a task calls for it.
mdr add dreadnode/capabilities/http-connection-contamination@git:20260529.8f6ea0ePins git:20260529.8f6ea0e in mdr.lock. Pin the fingerprint instead.
- Audit grade
- A, 17 of 17 checks passed
- Kind
- SKILL.md skill
- Repository
- dreadnode/capabilities
- Path
capabilities/web-security/skills/http-connection-contamination/SKILL.md- Versions recorded
- 2
- Latest version
- git:20260529.8f6ea0e, committed May 29, 2026
- First version recorded
- May 18, 2026
- Size
- 3,542 bytes
- Repository stars
- 22
- License
- MIT
Misroute requests across subdomains via HTTP/2+ connection coalescing on shared infrastructure with wildcard TLS certs. Use when target has multiple subdomains on same IP with wildcard cert and reverse proxy.
Collected from public GitHub. Every version is saved exactly as it was and never changes. Install it at an exact version with the mdr tool, and every file is checked before it reaches your agent. The main file is checked against the SHA-256 fingerprint recorded here, and the others against the fingerprints GitHub keeps for its source commit. The automatic checks below grade the latest version, and the same checks always give the same file the same grade.
What the file says
# HTTP Connection Contamination Browsers reuse HTTP/2+ connections across different origins when they share an IP and TLS certificate. If the reverse proxy routes by first request's Host header and reuses that routing for subsequent requests on the same connection, you can force requests to `secure.example.com` through `wordpress.example.com`'s backend. ## Prerequisites (all required) 1. Multiple subdomains resolve to **same IP** 2. **Wildcard TLS cert** covers both (e.g. `*.example.com`) 3. Reverse proxy uses **first-request routing** (routes connection based on initial Host header, not per-request) 4. Different backend applications behind different subdomains ## Why HTTP/3 Makes This Worse HTTP/2 coalescing requires same IP + shared cert. HTTP/3 (QUIC) relaxes the IP match requirement — the browser can coalesce connections to different IPs if the cert covers both origins. This broadens the attack surface without needing MITM or shared infrastructure. ## Probe ### Step 1: Check coalescing conditions ```bash # Same IP? dig +short sub1.example.com sub2.example.com # Shared cert? (check SAN/wildcard) …
Read the whole file at its exact version.
How to install
mdr add dreadnode/capabilities/http-connection-contamination@sha256:dcc60a127c24b13aThe line at the top of this page pins the label git:20260529.8f6ea0e, which is what most people want. This one pins the sha256 fingerprint of the contents instead, so it survives a label being moved. Either way the exact version is written to mdr.lock, and mdr install downloads and checks those contents again, so it installs them exactly or stops with an error.
[](https://markdownregistry.com/a/art_ta6jeywy3t4dhqbo)
3 badge image fetches in 30 days. What the badge shows.
Versions
The registry has recorded 2 versions of this file, between May 18, 2026 and May 29, 2026, about one every 11 days.
| version | committed | commit | size | audit | |
|---|---|---|---|---|---|
| git:20260529.8f6ea0e latest | 2026-05-29 | 8f6ea0e | 3,542 B | A | view · diff |
| git:20260518.7b5f854 | 2026-05-18 | 7b5f854 | 3,394 B | A | view |
Audit of the latest version
- pass: Frontmatter block present
- pass: Frontmatter declares a name
- pass: Frontmatter declares a description
- pass: Size between 200 bytes and 200 KB (3542 bytes)
- pass: No zero-width or bidi control characters
- pass: No instruction hidden inside an HTML comment
- pass: No link to an exfiltration or paste host
- pass: No credential-shaped string
- pass: No instruction to send local credentials anywhere
- pass: No text hidden with inline styles
- pass: No prompt-injection phrasing
- pass: No curl or wget piped into a shell
- pass: No recursive delete of root, home or parent
- pass: No instruction to read or print local credentials
- pass: No base64 blob over 200 characters
- pass: No link to a raw IP address
- pass: No script tag
Source
dreadnode/capabilities · 22 stars · license MIT · pushed 2026-11-02 · branch main
API
GET https://markdownregistry.com/api/v1/artifacts/art_ta6jeywy3t4dhqbo GET https://markdownregistry.com/api/v1/resolve?ref=dreadnode/capabilities/http-connection-contamination GET https://markdownregistry.com/api/v1/blob/dcc60a127c24b13ad5b7e3ef0c41f214986d3e3a87e424383a8d60eabe677b79
Your AI assistant does the legwork. You hear about the deals worth your word. Hand yours the standing instructions at modelranch.com and it joins the network that reads files like this one.
Guides: the SKILL.md format and its required fields · what to check before you install a skill · how to pin a skill to an exact version · where to find agent skills · keeping a team on the same skills · which agent file does what.