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crlf-injection

Detect CRLF injection vulnerabilities in HTTP response headers and bodies.

241|28|Updated May 20, 2026
Search Tags:#http response splitting#crlf injection#log injection#open redirect#cache poisoning#header injection#set-cookie
One-click install
npx skills add https://github.com/ok-helloworld/vibe-pentest --skill crlf-injection
Or copy as Structured Prompt for Agent▼
Please help me install this Agent Skill.
Skill: crlf-injection
Source: https://github.com/ok-helloworld/vibe-pentest/tree/main/references/pentest_skills/crlf-injection
Command: npx skills add https://github.com/ok-helloworld/vibe-pentest --skill crlf-injection

SYSTEM DOCUMENTATION & REQUIREMENTS

💡 This Skill includes references (resource) components.

What problem does it solve?

CRLF injection playbooks help you identify and validate whether user-controlled input can break HTTP header boundaries to inject new headers, response bodies, or cached content.

Core Features & Use Cases

  • Header injection & response splitting: Probe for %0D%0A-style payloads that create additional headers via redirect parameters, header-reflection points, or cookie construction.
  • Double-CRLF body injection: Use header/body boundary termination to test for injected HTML/JS in contexts where the server reflects the payload.
  • Attack chaining checks: Evaluate follow-on impact such as XSS escalation, session fixation via Set-Cookie, cache poisoning, redirect hijacking, and log injection.
  • Filter bypass guidance: Apply targeted encoding strategies like double-encoding and LF-only variations to confirm robustness of input handling.

Quick Start

Provide the target URL and the parameter (or header reflection point) where input reaches a redirect, header, cookie, or log field, then ask for a step-by-step CRLF injection validation plan including bypass attempts.

Frequently Asked Questions about crlf-injection

High-intent search queries and answers about installing and using this skill.

FAQPage Schema
How do I test for CRLF injection in HTTP response headers?▼

To test for CRLF injection, probe user-controlled inputs reaching redirect parameters or header reflection points with %0D%0A payloads to verify if the server splits HTTP response headers or injects additional headers.

What is HTTP response splitting and how does CRLF injection enable it?▼

HTTP response splitting occurs when CRLF injection breaks header boundaries, allowing attackers to terminate the original response and inject a new HTTP response body or malicious headers like Set-Cookie.

How can I bypass input filters when testing for CRLF injection?▼

You can bypass CRLF injection filters by applying targeted encoding strategies like double-encoding and LF-only variations to confirm the robustness of the server's input handling mechanisms.

Can CRLF injection lead to cache poisoning or open redirect vulnerabilities?▼

Yes, CRLF injection enables attack chaining including cache poisoning, open redirect hijacking, session fixation via Set-Cookie, and log injection across cacheable responses and log-visible fields.

How do I validate double-CRLF body injection in black-box testing?▼

Validate double-CRLF body injection by using header and body boundary termination probes to test for injected HTML or JavaScript in contexts where the server reflects the payload during black-box testing.

When should I check Set-Cookie construction for CRLF injection vulnerabilities?▼

Check Set-Cookie construction for CRLF injection when user-controlled input reaches cookie fields, allowing attackers to inject new headers and execute session fixation attacks via malicious cookie payloads.

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