Firefox Browser Add-ons
  • Extensions
  • Themes
    • for Firefox
    • Dictionaries & Language Packs
    • Other Browser Sites
    • Add-ons for Android
Log in
Preview of Ned - CVSS Calculator

Ned - CVSS Calculator by br0wnboi

Calculate CVSS 3.1 and 4.0 scores directly. Completely offline, with a built-in MITRE CWE database for fuzzy searching.

5 (2 reviews)5 (2 reviews)
Download Firefox and get the extension
Download file

Extension Metadata

About this extension
Calculate CVSS v3.1 & v4.0 scores completely offline. Ned is a blazing fast, elegantly designed browser extension built for cybersecurity professionals, pentesters, and vulnerability analysts who need an instant toolkit for their threat-scoring workflow without leaving the current tab.

Most online calculators risk exposing your proprietary threat data to external telemetry. Ned completely blocks all data leakage by operating 100% locally on your machine—no external API calls, tracking, or network traffic are ever sent out.

🌟 Key Features
- Dual Support: Instantly calculate Common Vulnerability Scoring System (CVSS) vectors using the official FIRST.org metrics for both v3.1 and v4.0 standards.
- MITRE CWE Database: A built-in, offline dictionary with advanced fuzzy searching to quickly look up Common Weakness Enumeration IDs (CWE). Search instantly through weakness names, extended descriptions, and alternate terms. Drill down into detailed weaknesses with clean, native expand/collapse dropdowns—no more jumping between tabs to find the right mapping!
- Zero Data Harvesting: Total offline-first privacy. No analytics, no telemetrics, no data collection.
- Copy & Paste Mastery: Click once to instantly copy a generated CVSS vector string or a CWE ID directly to your clipboard. Double-click the vector bar to quickly paste pre-existing strings to update all metric toggles automatically.
- Helpful Tooltips: Hover over complex metrics and CWE names to view detailed official descriptions natively inside the app.
- Persistent State: Ned remembers your selected tabs and exact metric calculations even after the browser window is closed, helping you resume work flawlessly.

💡 Designed for Speed
Built from the ground up to never get in your way. Whether you are generating bug bounty reports, triaging enterprise network alerts, or drafting CVEs, Ned remains the fastest, most private way to grade software vulnerabilities from your browser toolbar.

Open-Source libraries included: Official FIRST.org calculation modules (BSD-2-Clause) & Fuse.js (Apache-2.0).
Rated 5 by 2 reviewers
Log in to rate this extension
There are no ratings yet

Star rating saved

5
2
4
0
3
0
2
0
1
0
Read all 2 reviews
Permissions and data

Data collection:

  • The developer says this extension doesn't require data collection.
Learn more
More information
Add-on Links
  • Support Email
Version
1.4.2
Size
3.02 MB
Last updated
13 days ago (Mar 11, 2026)
Related Categories
  • Privacy & Security
  • Search Tools
  • Tabs
License
MIT License
Version History
  • See all versions
Add to collection
Report this add-on
Go to Mozilla's homepage

Add-ons

  • About
  • Firefox Add-ons Blog
  • Extension Workshop
  • Developer Hub
  • Developer Policies
  • Community Blog
  • Forum
  • Report a bug
  • Review Guide

Browsers

  • Desktop
  • Mobile
  • Enterprise

Products

  • Browsers
  • VPN
  • Relay
  • Monitor
  • Pocket
  • Bluesky (@firefox.com)
  • Instagram (Firefox)
  • YouTube (firefoxchannel)
  • Privacy
  • Cookies
  • Legal

Except where otherwise noted, content on this site is licensed under the Creative Commons Attribution Share-Alike License v3.0 or any later version.