Attack your own system — under explicit authorization — to prove its defenses hold, before launch and continuously after: scope and authorize, recon, scan and enumerate, exploit and confirm real vulnerabilities (not scanner false positives), chain them into real impact, then report and re-test. The offensive half of the security pair (the spear) that proves what the `aegis` skill builds (the shield). Authorized, defensive penetration testing of systems you own or have written permission to test — never anything else. Use when the user wants to penetration-test their own application before launch, validate a fix actually closed a hole, stand up adversarial validation in CI or on a cadence, or learn to test for OWASP-class vulnerabilities on their own staging. Triggers on "pentest my app", "attack my own system", "is this actually exploitable", "pre-launch security test", "red-team my staging", "test for SQL injection / XSS / IDOR", "set up continuous security validation", "OWASP testing".
About this skill (catalog notes)
Gungnir is published as a SKILL.md file in this catalog. At roughly 2,387 words the SKILL.md is on the longer end of the catalog distribution.
Gungnir sits in the Security category under the web-security sub-topic in the ClaudSkills catalog. There are 10 related skills indexed alongside it; comparing a few before installing usually reveals which fits your workflow best.
These notes are auto-generated from features detected in the SKILL.md file and from this catalog's structure — they aren't part of the source repository.
From the source SKILL.md
<!-- Copyright 2026 IamK77 — Licensed under the Apache License, Version 2.0. See ./LICENSE and ./NOTICE · https://www.apache.org/licenses/LICENSE-2.0 -->
What this skill does
Gungnir is a community-contributed Claude Code skill in the web-security sub-category. It ships as a SKILL.md file that Claude Code auto-discovers under ~/.claude/skills/gungnir/ and loads when your prompt matches the skill's trigger.
When to invoke it: Use when the user wants to penetration-test their own application before launch, validate a fix actually closed a hole, stand up adversarial validation in CI or on a cadence, or learn to test for OWASP-class vulnerabilities on their own staging. Triggers on "pentest my app", "attack my own system", "is this actually exploitable", "pre-launch security test", "red-team my staging", "test for SQL injection / XSS / IDOR", "set up continuous security validation", "OWASP testing".
Who uses this skill
The Gungnir Claude Code skill is built for security engineers, penetration testers, DevSecOps practitioners, and development teams hardening codebases and infrastructure. It's part of ClaudSkills (also referred to as Claude Skills or Claude Code Skills) — the open community-curated registry of 120,000+ SKILL.md files for Anthropic's Claude Code agent and the wider Claude ecosystem (Claude API, Claude Agent SDK).
Or just download SKILL.md directly and drop it into ~/.claude/skills/gungnir/. Claude Code auto-discovers it on next session.
Skills live at ~/.claude/skills/gungnir/SKILL.md on macOS/Linux, or %USERPROFILE%\.claude\skills\gungnir\SKILL.md on Windows. See the full install guide for step-by-step instructions.
Telegram
📱 Install from your phone or desktop Telegram
Open @claudskills_bot on Telegram, tap Open Desktop App, and the desktop app installs this skill for you. Or share the bot link with a colleague — they get the same one-tap install. Learn more →
Pro
One-click install via the desktop app
The ClaudSkills desktop app installs any skill directly into ~/.claude/skills/ with one click — no terminal required. Pro starts at $9/mo or $149 lifetime.
Pro
For the full experience including quality scoring and one-click install features for each skill — upgrade to Pro.
Install via the ClaudSkills desktop app (one click) or copy SKILL.md from the source repository to ~/.claude/skills/gungnir/SKILL.md and restart Claude Code. Both flows are detailed at claudskills.com/install/.
What does the Gungnir skill do?
Attack your own system — under explicit authorization — to prove its defenses hold, before launch and continuously after: scope and authorize, recon, scan and enumerate, exploit and confirm real vulnerabilities (not scanner false positives), chain them into real impact, then report and re-test. The offensive half of the security pair (the spear) that proves what the `aegis` skill builds (the shield). Authorized, defensive penetration testing of systems you own or have written permission to test — never anything else. Use when the user wants to penetration-test their own application before launch, validate a fix actually closed a hole, stand up adversarial validation in CI or on a cadence, or learn to test for OWASP-class vulnerabilities on their own staging. Triggers on "pentest my app", "attack my own system", "is this actually exploitable", "pre-launch security test", "red-team my staging", "test for SQL injection / XSS / IDOR", "set up continuous security validation", "OWASP testing".
Is this skill free to install?
Yes. ClaudSkills is an open registry — every skill keeps its source repository's license, and manual install via copy is free. ClaudSkills Pro ($9/mo, $79/yr, or $149 one-time) adds one-click install via the desktop app and a multi-signal Quality Score.
When should I use the Gungnir skill?
Use Gungnir when your Claude Code task falls under the Security category — specifically in the web security area. Claude Code auto-discovers installed skills and invokes the right one based on the task description, so you can also ask Claude directly (e.g. "use Gungnir" or describe the task and let Claude pick). Browse related skills at /category/security/.
What is a Claude Code skill and how does the Gungnir skill fit in?
A Claude Code skill is a SKILL.md file that lives under ~/.claude/skills/<name>/ and tells the Claude Code CLI agent how to perform a specific task (instructions, prompts, allowed tools). Skills are auto-discovered at session start. Gungnir is one of 67,000+ skills indexed in the open ClaudSkills catalog, classified under the Security category. Learn more at /learn/what-is-a-claude-skill/.
@misc{gungnir-2026,
author = {IamK77},
title = {Gungnir [Claude Code skill]},
year = {2026},
publisher = {ClaudSkills},
url = {https://claudskills.com/skills/gungnir/}
}
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Claude™ is a trademark of Anthropic PBC. ClaudSkills (also referred to as Claude Skills or Claude Code Skills Catalog) is an independent community-curated registry of SKILL.md files, not affiliated with, endorsed by, or sponsored by Anthropic.
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