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crlfuzz

v1.2.0 open-source

CRLFuzz is a fast tool written in Go that scans for CRLF vulnerabilities in URLs.

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Summary

crlfuzz is an open-source command-line tool, released under the MIT licence, that scans URLs for CRLF injection vulnerabilities using fuzzing techniques, written in Go. It is a single binary you point at a target with a flag, taking a single URL, a list of URLs from a file, or targets piped in from stdin, and it supports fuzzing with POST data or custom headers, plus a silent mode that prints only vulnerable URLs. This fits application security testers and penetration testers checking web apps for header-injection issues before or during a broader scan, and it sits in the web-app vulnerability scanning space alongside other Go-based fuzzers rather than being tied to one named competitor. Development is quiet but not dead: first committed in 2020 with three contributors, it has seen only two commits in the past year against eight releases in the tracked window.

CRLFuzz is a fast tool written in Go that scans for CRLF vulnerabilities in URLs.

How crlfuzz helps

Which of my endpoints are vulnerable to CRLF injection?

takes a single URL, a list from a file, or targets piped from another tool, fuzzes each one with injection payloads, and reports back which ones reflect attacker-controlled header or line breaks

Can I check a large batch of application URLs for header-injection flaws in one pass?

reads a file of URLs or a stream from stdin and fuzzes every one against the same payload set, so a whole crawl or asset list gets tested in a single run

Do custom headers my application relies on introduce a CRLF injection point?

accepts additional headers on the request and fuzzes with them included, surfacing injection through header values that a query-only scan would miss

Which URLs out of a huge scan actually need my attention?

a quiet mode suppresses everything except confirmed vulnerable URLs, so the output can feed straight into a report or another tool without manual filtering

Could malformed or unusual URLs in my target list be silently skipped instead of tested?

targets with raw control characters or malformed percent-escapes fail Go's URL parser before any request is sent, so those entries produce parse errors rather than a real vulnerability verdict

Languages

Not documented

Score card

  1. Shipping velocity releases a month, last 12 months
  2. Documentation quality release-notes rubric, 0–100
  3. Breaking-change discipline how rarely a release breaks users, and notice given
  4. Maintenance risk quiet time against its own cadence, maintainers
  5. Innovation & surface new capabilities, API and MCP surface
  6. Community health
  7. Contributor trend distinct committers, this year against last
  8. Maintainer concentration bus factor now against a year ago
  9. Issue backlog trend issues closed per issue opened, 12 months
  10. Responsiveness median time to a maintainer’s first reply

Nine scores for crlfuzz, each built from the releases, notes and API history this site tracks — and, on Researcher and Business, where it stands among every measured tool in its category and how that has moved.

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Each score is 0–100 on a published rubric, derived from data this site already shows. A dimension we cannot measure says so — it is never scored 0 and never enters a rank.

How this is scored
  • Shipping velocity — releases a month over the last 12 months, on a log scale where 16 a month scores 100. Needs 3 releases in the window.
  • Documentation quality — the release-notes rubric published on the analytics page, unchanged.
  • Breaking-change discipline — the share of releases carrying a breaking change (none scores 100, half or more scores 0). Only projects that label breaking changes are measured: a clean record cannot be told from an unlabelled one.
  • Maintenance risk — quiet time measured against the tool's own release cadence (quiet longer than 90 days and three typical gaps scores 0), plus the number of active maintainers and whether contributors are growing, where known. Higher is lower risk.
  • Innovation & surface — new capabilities in the feature ledger this year, API and MCP operations added, and the share of commits that are features: the mean of whichever we hold.
  • Community health (open-source tools only) — each is a direction, not a size: contributors this year against last, the bus factor now against a year ago, and issues closed per issue opened, where steady scores 50, doubled 100 and halved 0; plus the median time to a maintainer's first reply (an hour scores about 100, a month or more 0). A commercial card has no repository and carries none of the four.
  • Documented delivery (commercial tools) — when a vendor's documented new capabilities have slowed against its own baseline, that counts against the overall standing as heavily as two low dimensions. Steady delivery, or too little history to judge, leaves the standing alone; it is never a sixth score.
  • Open-source tools are scored on repository signals; commercial tools on their published changelog. Ranks compare tools within one category and one profile and need at least five measured peers; the overall standing needs three ranked dimensions. Best-in-breed or consolidator is a shape, not a quality, and is never scored.

Release-note detail over time

See how much detail crlfuzz puts in its release notes, quarter by quarter, and compare it with tracked tools in the same category. This history uses up to ten retained, reviewed notes per tool; sparse or blank older quarters may reflect that limit.

Checking release-note history…

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Releases

1 entry

  1. September 20201

    1 entry

    1. v1.2.0 Sep 14, 2020 · release notes

      crlfuzz v1.2.0 introduces escape_lists and rewrites URL string handling.

      └──▷ GET THIS VERSION 
      $ git clone --branch v1.2.0 https://github.com/dwisiswant0/crlfuzz.git
# already have the repo? check out this version:
$ git checkout v1.2.0
      • Adds the --escape_list CLI flag to define custom escape sequences for fuzzing
      • Supports escape_lists in .crlfuzz.yaml config file to manage escape rules persistently

      2 details in Everything

    Project health

    Issue, contributor and maintainer activity in dwisiswant0/crlfuzz, 2023-10 – 2026-09, as of 2026-09-25. Twelve-month figures first; the trend lines run the whole window.

    1. Contributors 0 ±0 vs prior 12 months
    2. Maintainers 0 +0 joined · −0 left, last 12 months
    3. Bus factor 0 committers behind half the commits
    4. Community-filed not measured of issues opened, last 12 months
    5. Median time to close not measured issues closed, last 12 months
    6. Open backlog 1 of 15 issues ever filed
    1. Issues opened / month 0 · 0 communitymaintainers
    2. Open backlog 1
    3. Contributors / month 0
    4. Commits / month 0
    5. Stars 1,566
    Issue themes, last 12 months not measured

    Counts from the project's public repository and git history; no individuals are identified. Maintainers are the committers covering 80% of the last year's commits. how we measure this

    Libraries its release ships

    What its latest release locks, checked against known advisories.

    None of its release's images build from a lockfile we can read.

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