crlf

A command that tests URLs and selected request headers for CRLF injection, also called HTTP response splitting. This is a flaw where inserted line breaks can add attacker-controlled headers to a response.

In plain words
What is it for?
Testing paths, query parameters and optionally host-related headers for CRLF injection, across one URL or a URL list, with optional JSON output.
Why use it?
The flaw can affect cookies, redirects, caches or password-reset links, but it may be hidden from ordinary page testing. The command checks whether its test header appears in the response.

Command

Install

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.

agentmods
npx agentmods add commands/awarexone/agentic-bug-hunter/crlf
Clone the repo
git clone --depth 1 https://github.com/Awarexone/Agentic-Bug-Hunter
Per session 0 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 506 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 1 finding. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

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.

ModelPer sessionOnce invoked
Fable 5 $0.00000 $0.00506
Opus 5 $0.00000 $0.00253
Sonnet 5 $0.00000 $0.00101
Haiku 4.5 $0.00000 $0.00051

Measured 2d ago against content hash 7f984f53b634, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

crlf scanned grade A 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 2d 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.

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

Python's `urllib` refuses raw `\r\n` in a URL (it protects you), so the
commands/crlf.md · 51 lines

What it actually says

/crlf

Inject carriage-return/line-feed sequences into the path/query (and optionally the Host/forwarding headers) and check whether an attacker-controlled header lands in the response — proof of CRLF injection.

Usage

/crlf "https://target.com/redirect?url=x"
/crlf https://target.com/ --host-header
/crlf -l recon/target.com/urls/params.txt --json

Run directly:

tools/crlf_scanner.py "https://target.com/r?u=x" --host-header

What it injects

Vector Payloads
Encoded CRLF %0d%0a, %0a, %0d, %250d%250a (double-encoded)
Header fold %0d%0a%20Set-Cookie:...
UTF-8 bypass %E5%98%8A%E5%98%8D (overlong CR/LF that defeats naive \r\n filters)
IIS unicode %u000d%u000a
Host-header Host: evil, X-Forwarded-Host, Forwarded: host=, CRLF-in-Host

Detection canary: the payloads try to inject Set-Cookie: crlftest=1. If that header appears in the response, it's confirmed.

Impact

  • Set-Cookie injection → session fixation.
  • Injected Location → open redirect / OAuth token theft.
  • Injected body → reflected XSS that survives CSP host allowlists.
  • Host-header injection → password-reset poisoning (attacker host in reset link), cache poisoning.

Note

Python's urllib refuses raw \r\n in a URL (it protects you), so the encoded variants are what actually go on the wire — that's intended. The host-header path also flags when your attacker host is reflected in a Location response header (reset-poisoning signal) even without a full CRLF.

Changes

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.

  1. 2d ago First seen · 51 lines · 0 tokens per session scan A 7f984f53b634

Subscribe to this mod's changes

crlf is a command published in the GitHub repository Awarexone/Agentic-Bug-Hunter (4,651 stars, last pushed yesterday), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 506 tokens. A static security scan graded it A with 1 finding (makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

Related

Other commands, from other repositories

recon

Run full recon pipeline on a target — subdomain enum (Chaos API + subfinder), live host discovery (dnsx + httpx), URL crawl (katana + waybackurls + gau), gf pattern classification, nuclei scan. Outputs to recon/ / directory. Usage: /recon target.com.

elementalsouls/Claude-BugHunter · 65 tokens

hunt

Active vulnerability hunting. Two-track dispatcher — asks Red Team vs WAPT, hands off to hunt-dispatch skill and sibling commands. Usage: /hunt target.com | /hunt .target.com | /hunt targets.txt [--vuln-class X] [--source-code P] [--chrome].

elementalsouls/Claude-BugHunter · 63 tokens

token-scan

Meme coin and token security scan — checks for rug pull vectors (hidden mint, honeypot, fee manipulation, LP lock bypass, authority retention, bonding curve exploits, fake renounce, sandwich amplification). Manual 8-class grep audit (with an optional automated scanner if present). Usage: /token-scan [--chain solana].

elementalsouls/Claude-BugHunter · 79 tokens

autopilot

Run autonomous hunt loop on a target — scope check → recon → rank surface → hunt → validate → report with configurable checkpoints. Usage: /autopilot target.com [--paranoid|--normal|--yolo].

elementalsouls/Claude-BugHunter · 49 tokens

triage

Quick 7-Question Gate triage on a finding before writing a report. Kills N/A submissions before they happen. Faster than /validate — for quick go/no-go decisions. Usage: /triage.

elementalsouls/Claude-BugHunter · 45 tokens

validate

Validate a finding — runs 7-Question Gate + 4-gate checklist. Kills weak findings before report writing. Prevents N/A submissions that hurt validity ratio. Usage: /validate.

elementalsouls/Claude-BugHunter · 41 tokens