Agent skill

API Auth And JWT Abuse

API authentication and JWT abuse playbook. An agent skill from yaklang/hack-skills.

Install API Auth And JWT Abuse

skills CLI

$ npx skills add yaklang/hack-skills --skill api-auth-and-jwt-abuse -a claude-code

Project install by default; add -g for ~/.claude/skills/.

GitHub CLI

$ gh skill install yaklang/hack-skills api-auth-and-jwt-abuse --agent claude-code

Project scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).

Manual copy

$ git clone --depth 1 https://github.com/yaklang/hack-skills.git skills-src && mkdir -p .claude/skills && cp -r skills-src/skills/api-auth-and-jwt-abuse .claude/skills/api-auth-and-jwt-abuse && rm -rf skills-src

Use ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.

Claude Code skills documentation · loads skills from .claude/skills/

Paste into Claude Code

Install the "api-auth-and-jwt-abuse" agent skill from https://github.com/yaklang/hack-skills/tree/main/skills/api-auth-and-jwt-abuse into .claude/skills/api-auth-and-jwt-abuse/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "api-auth-and-jwt-abuse", then confirm the skill loads.

Claude Code copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

$skill-installer

$skill-installer install https://github.com/yaklang/hack-skills/tree/main/skills/api-auth-and-jwt-abuse

Type this inside Codex. $skill-installer <name> installs a curated skill from openai/skills. The installer writes to $CODEX_HOME/skills (default ~/.codex/skills). Restart Codex if the skill does not show up.

skills CLI

$ npx skills add yaklang/hack-skills --skill api-auth-and-jwt-abuse -a codex

Project install goes to .agents/skills/; add -g for ~/.codex/skills/.

GitHub CLI

$ gh skill install yaklang/hack-skills api-auth-and-jwt-abuse --agent codex

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/yaklang/hack-skills.git skills-src && mkdir -p .agents/skills && cp -r skills-src/skills/api-auth-and-jwt-abuse .agents/skills/api-auth-and-jwt-abuse && rm -rf skills-src

Use ~/.agents/skills/ instead of .agents/skills for a personal install.

Codex skills documentation · loads skills from .agents/skills/

Paste into Codex

Install the "api-auth-and-jwt-abuse" agent skill from https://github.com/yaklang/hack-skills/tree/main/skills/api-auth-and-jwt-abuse into .agents/skills/api-auth-and-jwt-abuse/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "api-auth-and-jwt-abuse", then confirm the skill loads.

Codex copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

skills CLI

$ npx skills add yaklang/hack-skills --skill api-auth-and-jwt-abuse -a cursor

Project install goes to .agents/skills/; add -g for ~/.cursor/skills/.

GitHub CLI

$ gh skill install yaklang/hack-skills api-auth-and-jwt-abuse --agent cursor

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/yaklang/hack-skills.git skills-src && mkdir -p .cursor/skills && cp -r skills-src/skills/api-auth-and-jwt-abuse .cursor/skills/api-auth-and-jwt-abuse && rm -rf skills-src

Use ~/.cursor/skills/ instead of .cursor/skills for a personal install.

Cursor skills documentation · loads skills from .cursor/skills/, .agents/skills/, .claude/skills/, .codex/skills/

Paste into Cursor

Install the "api-auth-and-jwt-abuse" agent skill from https://github.com/yaklang/hack-skills/tree/main/skills/api-auth-and-jwt-abuse into .cursor/skills/api-auth-and-jwt-abuse/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "api-auth-and-jwt-abuse", then confirm the skill loads.

Cursor copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

gemini skills install

$ gemini skills install https://github.com/yaklang/hack-skills.git --path skills/api-auth-and-jwt-abuse

--scope user (default) or --scope workspace; --path is the subfolder of the repo that holds the skill; --consent skips the security confirmation prompt.

skills CLI

$ npx skills add yaklang/hack-skills --skill api-auth-and-jwt-abuse -a gemini-cli

Project install goes to .agents/skills/; add -g for ~/.gemini/skills/.

GitHub CLI

$ gh skill install yaklang/hack-skills api-auth-and-jwt-abuse --agent gemini-cli

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/yaklang/hack-skills.git skills-src && mkdir -p .gemini/skills && cp -r skills-src/skills/api-auth-and-jwt-abuse .gemini/skills/api-auth-and-jwt-abuse && rm -rf skills-src

Use ~/.gemini/skills/ instead of .gemini/skills for a personal install, then run /skills reload.

Gemini CLI skills documentation · loads skills from .gemini/skills/, .agents/skills/

Paste into Gemini CLI

Install the "api-auth-and-jwt-abuse" agent skill from https://github.com/yaklang/hack-skills/tree/main/skills/api-auth-and-jwt-abuse into .gemini/skills/api-auth-and-jwt-abuse/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "api-auth-and-jwt-abuse", then confirm the skill loads.

Gemini CLI copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

GitHub CLI

$ gh skill install yaklang/hack-skills api-auth-and-jwt-abuse

Installs for Copilot at project scope by default; add --scope user for a personal install. Preview a skill first with gh skill preview. Needs GitHub CLI 2.90.0 or later (public preview).

skills CLI

$ npx skills add yaklang/hack-skills --skill api-auth-and-jwt-abuse -a github-copilot

Project install goes to .agents/skills/; add -g for ~/.copilot/skills/.

Manual copy

$ git clone --depth 1 https://github.com/yaklang/hack-skills.git skills-src && mkdir -p .github/skills && cp -r skills-src/skills/api-auth-and-jwt-abuse .github/skills/api-auth-and-jwt-abuse && rm -rf skills-src

Use ~/.copilot/skills/ instead of .github/skills for a personal install. Commit .github/skills so cloud agent and code review can use it.

GitHub Copilot skills documentation · loads skills from .github/skills/, .claude/skills/, .agents/skills/

Paste into GitHub Copilot

Install the "api-auth-and-jwt-abuse" agent skill from https://github.com/yaklang/hack-skills/tree/main/skills/api-auth-and-jwt-abuse into .github/skills/api-auth-and-jwt-abuse/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "api-auth-and-jwt-abuse", then confirm the skill loads.

GitHub Copilot copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

skills CLI

$ npx skills add yaklang/hack-skills --skill api-auth-and-jwt-abuse -a opencode

OpenCode documents no install command of its own. Project install goes to .agents/skills/; add -g for ~/.config/opencode/skills/.

GitHub CLI

$ gh skill install yaklang/hack-skills api-auth-and-jwt-abuse --agent opencode

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/yaklang/hack-skills.git skills-src && mkdir -p .opencode/skills && cp -r skills-src/skills/api-auth-and-jwt-abuse .opencode/skills/api-auth-and-jwt-abuse && rm -rf skills-src

Use ~/.config/opencode/skills/ instead of .opencode/skills for a personal install.

OpenCode skills documentation · loads skills from .opencode/skills/, .claude/skills/, .agents/skills/

Paste into OpenCode

Install the "api-auth-and-jwt-abuse" agent skill from https://github.com/yaklang/hack-skills/tree/main/skills/api-auth-and-jwt-abuse into .opencode/skills/api-auth-and-jwt-abuse/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "api-auth-and-jwt-abuse", then confirm the skill loads.

OpenCode copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

Facts

Skill name: api-auth-and-jwt-abuse
GitHub stars: 2.4k
Token cost: ~567 tokens
SKILL.md length: 223 words
Files: 1
Skills in repo: 27
Repo updated: Sep 13, 2026
First seen: Oct 7, 2026
Licence: MIT

At a glance

API authentication and JWT abuse playbook. An agent skill from yaklang/hack-skills.

Works in 5 steps: TOKEN TRIAGE → QUICK ATTACK PICKS → HIDDEN FIELDS AND BATCH ABUSE → …
Testing bearer tokens
SKILL.md covers 1. TOKEN TRIAGE, 2. QUICK ATTACK PICKS, 3. HIDDEN FIELDS AND BATCH ABUSE and 4. RATE LIMIT BYPASS FAMILIES, plus 1 more section
Instructions only: no scripts, shell commands, URLs or credentials in SKILL.md

What it does

API Auth And JWT Abuse is an agent skill from yaklang/hack-skills. API authentication and JWT abuse playbook. Use when testing bearer tokens, API keys, claim trust, header spoofing, rate limits, and API auth boundary weaknesses.

Its SKILL.md is about 570 tokens, which your agent loads only when the skill is triggered. It is a single SKILL.md file with no bundled scripts.

It sits in Backend & APIs, covering Authentication and Rate limiting. It works with GraphQL. The repository describes itself as: Helping AI Agent become an awesome practical hacker! The licence is MIT.

When your agent uses it

Testing bearer tokens
Header spoofing
API auth boundary weaknesses

Example prompts

“/api-auth-and-jwt-abuse”

Workflow steps

5 steps, taken from the step headings in SKILL.md.

TOKEN TRIAGE
QUICK ATTACK PICKS
HIDDEN FIELDS AND BATCH ABUSE
RATE LIMIT BYPASS FAMILIES
NEXT ROUTING

What it can do on your machine

Read from SKILL.md and the folder at commit 6fbf0bc. It shows what the files ask for, not the result of running them.

Tool permissions
Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.
From allowed-tools in the SKILL.md frontmatter.
Runs code
No scripts in the folder and no shell commands in SKILL.md.
From the folder's file list and the shell code blocks in SKILL.md.
Network
No URLs in SKILL.md.
From URLs in SKILL.md, links to its own repository left out.
Credentials
Names no API keys, tokens, secrets or passwords.
From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

API Auth And JWT Abuse loads about 567 tokens when it runs. Until then it costs about 46 tokens; SKILL.md has 223 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it: ~46
When it runs · the whole SKILL.md, loaded when a task matches: ~567

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Auto-check passed

The automated check found no risky patterns in SKILL.md.

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from yaklang/hack-skills at commit 6fbf0bc, republished under its MIT licence (© yaklang). 223 words, ~567 tokens.

Download SKILL.mdSave it as .claude/skills/api-auth-and-jwt-abuse/SKILL.md (or your agent's skills folder).

name: api-auth-and-jwt-abuse
description: API authentication and JWT abuse playbook. Use when testing bearer tokens, API keys, claim trust, header spoofing, rate limits, and API auth boundary weaknesses.

SKILL: API Auth and JWT Abuse — Token Trust, Header Tricks, and Rate Limits

AI LOAD INSTRUCTION: Use this skill when APIs rely on JWT, bearer tokens, API keys, or weak request identity signals. Focus on token trust boundaries, claim misuse, header spoofing, and rate-limit bypass.

1. TOKEN TRIAGE

Inspect:

alg, kid, jku, x5u
role, org, tenant, scope, or privilege claims
issuer and audience mismatches
reuse of mobile and web tokens across products

2. QUICK ATTACK PICKS

Pattern	First Test
`alg:none` acceptance	unsigned token with trailing dot
RS256 confusion	switch to HS256 using public key as secret
`kid` lookup trust	path traversal or injection in `kid`
remote key fetch trust	attacker-controlled `jku` or `x5u`
weak secret	offline crack with targeted wordlists

3. HIDDEN FIELDS AND BATCH ABUSE

Mass assignment field picks

text

role
isAdmin
admin
verified
plan
tier
permissions
org
owner

Rate limit and batch abuse picks

text

X-Forwarded-For: 1.2.3.4
X-Real-IP: 5.6.7.8
Forwarded: for=9.9.9.9

GraphQL or JSON batch abuse candidates:

arrays of login mutations
bulk object fetches with varying IDs
repeated password reset or verification calls in one request

4. RATE LIMIT BYPASS FAMILIES

text

X-Forwarded-For
X-Real-IP
Forwarded
User-Agent rotation
Path case / slash variants

5. NEXT ROUTING

For GraphQL batching and hidden parameters: graphql and hidden parameters
For default credential and brute-force planning: authentication bypass
For full JWT and OAuth depth: jwt oauth token attacks
For OAuth or OIDC configuration flaws in browser and SSO flows: oauth oidc misconfiguration
For credentialed browser reads and origin trust bugs: cors cross origin misconfiguration

Files

Just SKILL.md in skills/api-auth-and-jwt-abuse of yaklang/hack-skills.

Open the folder on GitHubat commit 6fbf0bc

Compare with similar skills

API Auth And JWT Abuse next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.

API Auth And JWT Abuse compared with similar skills
Skill	Stars	Used in	Tokens	Auto-check	Licence	Repo updated
API Auth And JWT Abuse this skillyaklang/hack-skills	2.4k	—	~567	Automated safety check: Pass	MIT	27 days ago
API Auditbriiirussell/cybersecurity-skills	413	—	~2.8k	Automated safety check: Notes	MIT	4 mo ago
Domain Webfjrevoredo/mini-diarium	309	1 repos	~1k	Automated safety check: Pass	MIT	yesterday
Discover APIrand/cc-polymath	181	—	~1.5k	Automated safety check: Pass	MIT	7 mo ago
API Connector Builderericrisco/rsc-harness	180	—	~3.6k	Automated safety check: Pass	MIT	yesterday
Hunt APIEncod3d-Sec/TORCH	329	—	~1.9k	Automated safety check: Pass	MIT	1 mo ago

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Questions about API Auth And JWT Abuse

What does API Auth And JWT Abuse do?

API authentication and JWT abuse playbook. An agent skill from yaklang/hack-skills. API Auth And JWT Abuse is an agent skill from yaklang/hack-skills. API authentication and JWT abuse playbook.

When should I use API Auth And JWT Abuse?

API Auth And JWT Abuse fits situations like: testing bearer tokens; header spoofing; API auth boundary weaknesses.

How do I install API Auth And JWT Abuse in Claude Code?

Run `npx skills add yaklang/hack-skills --skill api-auth-and-jwt-abuse -a claude-code`. Or copy the skill folder (skills/api-auth-and-jwt-abuse in yaklang/hack-skills) into .claude/skills/api-auth-and-jwt-abuse in your project. Claude Code loads it when a task matches its description.

How do I install API Auth And JWT Abuse in Codex?

Run `npx skills add yaklang/hack-skills --skill api-auth-and-jwt-abuse -a codex`. Or copy the skill folder (skills/api-auth-and-jwt-abuse in yaklang/hack-skills) into .agents/skills/api-auth-and-jwt-abuse in your project. Codex loads it when a task matches its description.

Can I use API Auth And JWT Abuse in Cursor, Gemini CLI or GitHub Copilot?

Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add yaklang/hack-skills --skill api-auth-and-jwt-abuse -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/api-auth-and-jwt-abuse, .gemini/skills/api-auth-and-jwt-abuse, .github/skills/api-auth-and-jwt-abuse and .opencode/skills/api-auth-and-jwt-abuse in your project.

What does API Auth And JWT Abuse need to run?

SKILL.md names no scripts, command-line tools or credentials: API Auth And JWT Abuse is instructions for the agent only.

Does API Auth And JWT Abuse access the network?

SKILL.md contains no URLs. Any network use would come from the scripts or tools the agent runs. This is read from the text; nothing was executed.

Is API Auth And JWT Abuse safe to install?

Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. Review the folder before installing.

What licence does API Auth And JWT Abuse use?

API Auth And JWT Abuse is published under the MIT licence (the repository's licence). It allows redistribution, so the full SKILL.md is shown on this page.

How many tokens does API Auth And JWT Abuse use?

About 567 tokens (SKILL.md is roughly 2.3k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full.

What are the alternatives to API Auth And JWT Abuse?

Skills that share tags, products or a category with API Auth And JWT Abuse: API Audit (briiirussell/cybersecurity-skills, 413 stars), Domain Web (fjrevoredo/mini-diarium, 309 stars), Discover API (rand/cc-polymath, 181 stars) and API Connector Builder (ericrisco/rsc-harness, 180 stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains API Auth And JWT Abuse?

yaklang (a GitHub organization) maintains it in yaklang/hack-skills, which has 2,418 GitHub stars. The repository holds 27 skills in this directory. The repository was last updated on September 13, 2026.

Source: yaklang/hack-skills on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.

Install API Auth And JWT Abuse

Facts

At a glance

What it does

When your agent uses it

Example prompts

Workflow steps

What it can do on your machine

Tool permissions

Runs code

Network

Credentials

Context cost

Safety

SKILL.md

SKILL: API Auth and JWT Abuse — Token Trust, Header Tricks, and Rate Limits

1. TOKEN TRIAGE

2. QUICK ATTACK PICKS

3. HIDDEN FIELDS AND BATCH ABUSE

Mass assignment field picks

Rate limit and batch abuse picks

4. RATE LIMIT BYPASS FAMILIES

5. NEXT ROUTING

Files

Compare with similar skills

Similar skills

More from yaklang/hack-skills

Related

Questions about API Auth And JWT Abuse