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Agent skill

Nextjs Security

by HoangNguyen0403 in HoangNguyen0403/agent-skills-standard

Secure Next.js App Router with middleware auth, Server Action validation, CSP headers, and taint APIs.

MITAuto-check passedBackend & APIs

Install Nextjs Security

skills CLI
$ npx skills add HoangNguyen0403/agent-skills-standard --skill nextjs-security -a claude-code

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

GitHub CLI
$ gh skill install HoangNguyen0403/agent-skills-standard nextjs-security --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/HoangNguyen0403/agent-skills-standard.git skills-src && mkdir -p .claude/skills && cp -r skills-src/skills/nextjs/nextjs-security .claude/skills/nextjs-security && 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/

Facts

Skill name
nextjs-security
GitHub stars
572
Token cost
~688 tokens
SKILL.md length
265 words
Files
3 (incl. references)
Skills in repo
211
Repo updated
First seen
Licence
MIT

At a glance

Secure Next.js App Router with middleware auth, Server Action validation, CSP headers, and taint APIs.

  • Works in 5 steps: Add auth middleware — Create… → Validate Server Actions — Parse all… → Set security headers — Add CSP, HSTS,… → …
  • Adding authentication middleware
  • SKILL.md covers Priority: P0 (CRITICAL), Workflow: Secure Next.js App, Secure Server Action Example and Implementation Guidelines, plus 2 more sections
  • Instructions only: no scripts, shell commands, URLs or credentials in SKILL.md

What it does

Nextjs Security is an agent skill from HoangNguyen0403/agent-skills-standard. Secure Next.js App Router with middleware auth, Server Action validation, CSP headers, and taint APIs. Use when adding authentication middleware, validating Server Action inputs with Zod, or preventing secret leakage to client bundles.

Its SKILL.md is about 690 tokens, which your agent loads only when the skill is triggered. The skill folder holds 4 other files, including reference files (for example `evals/evals.json` and `references/implementation.md`).

It sits in Backend & APIs, covering Forms and validation and Authentication. It works with Next.js and Zod. The repository describes itself as: A collection of Agent Skills Standard and Best Practice for Programming Languages, Frameworks that help our AI Agent follow best practies on frameworks and programming laguages. The licence is MIT.

When your agent uses it

  • Adding authentication middleware
  • Validating Server Action inputs with Zod
  • Preventing secret leakage to client bundles

Example prompts

  • “/nextjs-security”

Workflow steps

5 steps, taken from the first numbered list in SKILL.md.

  1. Add auth middleware — Create middleware.ts to verify JWT/session on protected routes.
  2. Validate Server Actions — Parse all inputs with Zod schemas; call await auth() first.
  3. Set security headers — Add CSP, HSTS, X-Frame-Options in middleware response.
  4. Use server-only — Import in modules containing secrets to prevent client bundling.
  5. Taint sensitive objects — Use taintObjectReference to block server objects from reaching client.

What it can do on your machine

Read from SKILL.md and the folder at commit b529c2d. 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

Nextjs Security loads about 688 tokens when it runs, and up to ~971 if it reads all its reference files. Until then it costs about 63 tokens; SKILL.md has 265 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it
~63
When it runs · the whole SKILL.md, loaded when a task matches
~688
With references · SKILL.md plus every file in references/, read only if the agent opens them
~971

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 HoangNguyen0403/agent-skills-standard at commit b529c2d, republished under its MIT licence (© HoangNguyen0403). 265 words, ~688 tokens.

Download SKILL.mdSave it as .claude/skills/nextjs-security/SKILL.md (or your agent's skills folder). This skill also uses 2 other files; get the full folder from GitHub.
name
nextjs-security
description
Secure Next.js App Router with middleware auth, Server Action validation, CSP headers, and taint APIs. Use when adding authentication middleware, validating Server Action inputs with Zod, or preventing secret leakage to client bundles.

Next.js Security

Priority: P0 (CRITICAL)

Workflow: Secure Next.js App

  1. Add auth middleware — Create middleware.ts to verify JWT/session on protected routes.
  2. Validate Server Actions — Parse all inputs with Zod schemas; call await auth() first.
  3. Set security headers — Add CSP, HSTS, X-Frame-Options in middleware response.
  4. Use server-only — Import in modules containing secrets to prevent client bundling.
  5. Taint sensitive objects — Use taintObjectReference to block server objects from reaching client.

Secure Server Action Example

See implementation examples

Implementation Guidelines

  • Next.js Middleware: Use middleware.ts for edge-side authentication, role-based access control (RBAC), and enforcing Security Headers (e.g., Content-Security-Policy (CSP), X-XSS-Protection).
  • Server Actions: Always sanitize all inputs from FormData or JSON using Zod. Perform authentication checks (await auth()) inside every action to verify caller.
  • Data Tainting: Use experimental_taint API (taintObjectReference) to ensure sensitive server objects (e.g., User with passwordHash) never leak into Client Component.
  • Route Handlers (route.ts): Implement rate limiting to prevent brute-force or DoS attacks. Verify Origin/Referer headers to mitigate CSRF (Cross-Site Request Forgery).
  • Auth Tokens: strictly use HttpOnly, Secure cookies with SameSite: 'Lax' for session management. Never store tokens in localStorage.
  • Logic Isolation: use server-only package to prevent backend-specific logic from included in client bundle.
  • Component Purity: Escape all user-provided content rendered in components. Never use dangerouslySetInnerHTML without sanitizer like DOMPurify.

Anti-Patterns

  • No leaking DB fields to client: Use DTOs; never pass raw model objects.
  • No process.env in client bundles: Mark as NEXT_PUBLIC_ only if safe to expose.
  • No unvalidated Server Action inputs: Always validate with Zod schema.
  • No auth checks in shared Layouts: Auth in layouts insecure; use Middleware.

References

© HoangNguyen0403, MIT. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

SKILL.md and 2 other files (references) in skills/nextjs/nextjs-security of HoangNguyen0403/agent-skills-standard.

  • SKILL.md
  • evals/evals.json
  • references/implementation.md

Open the folder on GitHubat commit b529c2d

Compare with similar skills

Nextjs Security 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.

Nextjs Security compared with similar skills
SkillStarsUsed inTokensAuto-checkLicenceRepo updated
Nextjs Security this skillHoangNguyen0403/agent-skills-standard572—~688Automated safety check: PassMIT
Backend Dev Guidelineslitefuse/litefuse1011 repos~5.8kAutomated safety check: PassCustom licence
Frontend Patterns Templatebybren-llc/safe-agentic-workflow423—~2kAutomated safety check: PassMIT
Inngest Nextjs Patternspproenca/dot-skills215—~1.4kAutomated safety check: NotesMIT
API Testingpetrkindlmann/qa-skills170—~2.7kAutomated safety check: PassMIT
Arkenvyamcodes/arkenv147—~2.5kAutomated safety check: PassMIT

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Works with

Categories

Questions about Nextjs Security

What does Nextjs Security do?

Secure Next.js App Router with middleware auth, Server Action validation, CSP headers, and taint APIs. Nextjs Security is an agent skill from HoangNguyen0403/agent-skills-standard.js App Router with middleware auth, Server Action validation, CSP headers, and taint APIs.

When should I use Nextjs Security?

Nextjs Security fits situations like: adding authentication middleware; validating Server Action inputs with Zod; preventing secret leakage to client bundles.

How do I install Nextjs Security in Claude Code?

Run `npx skills add HoangNguyen0403/agent-skills-standard --skill nextjs-security -a claude-code`. Or copy the skill folder (skills/nextjs/nextjs-security in HoangNguyen0403/agent-skills-standard) into .claude/skills/nextjs-security in your project. Claude Code loads it when a task matches its description.

How do I install Nextjs Security in Codex?

Run `npx skills add HoangNguyen0403/agent-skills-standard --skill nextjs-security -a codex`. Or copy the skill folder (skills/nextjs/nextjs-security in HoangNguyen0403/agent-skills-standard) into .agents/skills/nextjs-security in your project. Codex loads it when a task matches its description.

Can I use Nextjs Security 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 HoangNguyen0403/agent-skills-standard --skill nextjs-security -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/nextjs-security, .gemini/skills/nextjs-security, .github/skills/nextjs-security and .opencode/skills/nextjs-security in your project.

What does Nextjs Security need to run?

SKILL.md names no scripts, command-line tools or credentials: Nextjs Security is instructions for the agent only.

Does Nextjs Security 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 Nextjs Security 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 Nextjs Security use?

Nextjs Security 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 Nextjs Security use?

About 688 tokens (SKILL.md is roughly 2.8k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full. Its references folder adds about 283 tokens, read only when the agent opens those files.

What are the alternatives to Nextjs Security?

Skills that share tags, products or a category with Nextjs Security: Backend Dev Guidelines (litefuse/litefuse, 101 stars), Frontend Patterns Template (bybren-llc/safe-agentic-workflow, 423 stars), Inngest Nextjs Patterns (pproenca/dot-skills, 215 stars) and API Testing (petrkindlmann/qa-skills, 170 stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Nextjs Security?

HoangNguyen0403 (a GitHub user) maintains it in HoangNguyen0403/agent-skills-standard, which has 572 GitHub stars. The repository holds 211 skills in this directory. The repository was last updated on October 9, 2026.

Source: HoangNguyen0403/agent-skills-standard on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.