crlf-injection

Detects CRLF injection flaws in HTTP headers, redirects, cookies, and log fields.

11|4|Updated Jun 7, 2026

Search Tags:#xss #web-security #session-fixation #header-injection #cache-poisoning #crlf-injection #response-splitting

Ready to run

npx skills add https://github.com/sayseven7/frameseven --skill crlf-injection-sayseven7

💬 Prompt for ChatGPT / Claude Chat▼

Please help me install this Agent Skill.
Skill: crlf-injection
Source: https://github.com/sayseven7/frameseven/tree/main/internal/mcp/skills/crlf-injection
Command: npx skills add https://github.com/sayseven7/frameseven --skill crlf-injection-sayseven7

SYSTEM DOCUMENTATION & REQUIREMENTS

What problem does it solve?

This Skill helps identify and validate CRLF injection flaws where untrusted input reaches HTTP headers, redirect targets, cookies, or log sinks and can split responses or forge downstream content.

Core Features & Use Cases

Header and redirect testing: Checks whether user-controlled values can inject new headers, alter Location behavior, or trigger response splitting.
Payload and bypass analysis: Explores double CRLF body injection, encoding tricks, and partial newline variants that often evade naive filters.
Security impact review: Assesses exploit chains such as session fixation, reflected content injection, cache poisoning, and log forgery in authorized testing.

Quick Start

Use the crlf-injection skill to test an authorized parameter for response-splitting behavior, then summarize any injected headers, body breaks, or cache-poisoning evidence.

Frequently Asked Questions about crlf-injection

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

FAQPage Schema

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

CRLF injection occurs when untrusted input injects carriage-return and line-feed characters into HTTP headers, splitting responses or forging downstream content by breaking header boundaries and injecting new headers or body content.

How do I test redirect parameters and cookie values for response splitting behavior?▼

Test redirect parameters and cookie values by injecting CRLF sequences to alter Location behavior and trigger response splitting, validating whether untrusted input can forge new headers or break response bodies during authorized security testing.

Can encoding bypasses and double CRLF injection evade naive security filters?▼

Encoding bypasses and double CRLF body injection exploit partial newline variants and encoding tricks to evade naive filters, successfully splitting HTTP responses and forging downstream content when basic input validation is applied.

What security vulnerabilities can CRLF injection exploit beyond HTTP response splitting?▼

CRLF injection can chain into session fixation, reflected content injection, cache poisoning, and log forgery, manipulating header-processing paths to alter downstream content and session behavior in authorized testing scenarios.

How do I confirm exploitable header manipulation in log fields and redirect targets?▼

Confirm exploitable header manipulation by validating injected headers and body breaks in log fields and redirect targets, checking whether untrusted input successfully splits responses or forges downstream content during authorized assessments.