crlf-response-splitting SKILL.md skillB
crlf-response-splitting 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/crlf-response-splitting@git:20260529.8f6ea0ePins git:20260529.8f6ea0e in mdr.lock. Pin the fingerprint instead.
- Audit grade
- B, 16 of 17 checks passed
- Kind
- SKILL.md skill
- Repository
- dreadnode/capabilities
- Path
capabilities/web-security/skills/crlf-response-splitting/SKILL.md- Versions recorded
- 2
- Latest version
- git:20260529.8f6ea0e, committed May 29, 2026
- First version recorded
- May 4, 2026
- Size
- 2,733 bytes
- Repository stars
- 22
- License
- MIT
Nested response splitting to bypass strict CSP via CRLF injection. Turns header injection into XSS even when script-src is self only. Use when CRLF injection is confirmed in response headers and CSP blocks inline or external scripts.
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
# CRLF Injection -> Nested Response Splitting CSP Bypass ## Pattern - CRLF injection exists in a response header such as `Content-Type` or `Location` - CSP is strict enough to block inline script execution - You can inject `\r\n\r\n` and split the response body - Inline payloads are blocked by CSP, so you need a same-origin script gadget ## Core Technique Use one CRLF-injectable endpoint to return HTML and load a second same-origin CRLF-injectable endpoint as JavaScript. ``` Outer split: <script src="/vuln-endpoint?type=text/javascript%0d%0a%0d%0aalert(origin)//PADDING"> Inner split: response with Content-Type: text/javascript and body alert(origin) ``` The nested request is same-origin, so `script-src 'self'` permits execution. ## Truncation Methods ### Missing Content-Length Inject a shorter `Content-Length` in the nested response: ``` Content-Length: 13\r\n\r\nalert(origin) ``` ### Transfer-Encoding: chunked For HTTP/1.1 targets: ``` Transfer-Encoding: chunked\r\n\r\nd\r\nalert(origin)\r\n0\r\n\r\n ``` ### Fixed Content-Length padding Pad the payload with a JavaScript comment and filler bytes: ``` alert(origin)//AAAAAAAAAAAA ``` ## Payload Construction …
Read the whole file at its exact version.
How to install
mdr add dreadnode/capabilities/crlf-response-splitting@sha256:fbcdacf572074a43The 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_4hyhvmf6ufn4gl3w)
3 badge image fetches in 30 days. What the badge shows.
Versions
The registry has recorded 2 versions of this file, between May 4, 2026 and May 29, 2026, about one every 25 days.
| version | committed | commit | size | audit | |
|---|---|---|---|---|---|
| git:20260529.8f6ea0e latest | 2026-05-29 | 8f6ea0e | 2,733 B | B | view · diff |
| git:20260504.2a64374 | 2026-05-04 | 2a64374 | 2,380 B | B | view |
Audit of the latest version
- fail: No script tag (matched: <script)
- pass: Frontmatter block present
- pass: Frontmatter declares a name
- pass: Frontmatter declares a description
- pass: Size between 200 bytes and 200 KB (2733 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
Starting a new one? Use a template for SKILL.md on mdpantry, which passes every one of these checks and says what to change in it.
Source
dreadnode/capabilities · 22 stars · license MIT · pushed 2026-11-02 · branch main
API
GET https://markdownregistry.com/api/v1/artifacts/art_4hyhvmf6ufn4gl3w GET https://markdownregistry.com/api/v1/resolve?ref=dreadnode/capabilities/crlf-response-splitting GET https://markdownregistry.com/api/v1/blob/fbcdacf572074a434dcbf8a487d5c2aa543e7be9d1875083f3a414c910c515fa
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.