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Security audit

Nextjs App Router Audit

Security checks for vulnerabilities and agentic risk

Overview

This is a local Next.js audit skill with a read-only scanner; I found no hidden network access, persistence, or destructive behavior.

Install only if you are comfortable letting the agent read the Next.js project source you ask it to audit. The reviewed scanner is local and read-only, but its reports are heuristic leads that should be verified before applying code changes.

Vulnerability Patterns
  • Skill Instruction HijackingAlters the agent's session goals or safety constraints when the skill loads
  • Agent Memory PoisoningWrites attacker-controlled rules into memory that affect later sessions
  • Remote Payload Retrieval and ExecutionFetches external code whose behavior can change after review
  • Embedded Malicious CodeShips malicious scripts inside the skill and executes them locally
  • Unauthorized Access and Privilege EscalationObtains permissions beyond the task's legitimate needs
Vulnerability Patterns
  • Data ExfiltrationExternal Transmission, Env Variable Harvesting, File System Enumeration
  • Supply ChainUnpinned Dependencies, External Script Fetching, Obfuscated Code
  • Trigger AbuseOverly Broad Trigger, Shadow Command Trigger, Keyword Baiting Trigger
  • MCP Least PrivilegeUnderdeclared Capability, Wildcard Permission, Missing Permission Declaration
  • Prompt InjectionInstruction Override, Hidden Instructions, Exfiltration Commands
Findings (9)

Ae1

High
Category
analysis-evasion
Confidence
100% confidence
Finding

Referenced artifact was not completely inspected

Content

Scanner excerpt · SKILL.md (reported line 3)May include surrounding context.

md
r why metadata/SEO tags aren't showing. Ships a zero-dependency static scanner (scripts/audit.mjs) plus a manual review methodology for things static analysis c

Ae1

High
Category
analysis-evasion
Confidence
100% confidence
Finding

Referenced artifact was not completely inspected

Content

Scanner excerpt · SKILL.md (reported line 19)May include surrounding context.

md
r why metadata/SEO tags aren't showing. Ships a zero-dependency static scanner (scripts/audit.mjs) plus a manual review methodology for things static analysis c

Ae1

High
Category
analysis-evasion
Confidence
100% confidence
Finding

Referenced artifact was not completely inspected

Content

Scanner excerpt · SKILL.md (reported line 20)May include surrounding context.

md
r why metadata/SEO tags aren't showing. Ships a zero-dependency static scanner (scripts/audit.mjs) plus a manual review methodology for things static analysis c

Skill Enumeration

Medium
Category
Agent Snooping
Confidence
85% confidence
Finding

Skill enumerates or reads other installed skills. Access to other skills' SKILL.md files or the skills directory reveals prompt instructions, capabilities, and secrets that should be invisible to peer skills.

Content

Scanner excerpt · README.md (reported line 55)May include surrounding context.

md
## Use it as a Claude skill

Place the folder in your skills directory (e.g. `~/.claude/skills/`) or upload it
to your skills hub, then ask:

> "Audit this Next.js app for performance and RSC problems."

Vague Triggers

Medium
Category
Not specified by scanner
Confidence
89% confidence
Finding

The example trigger "Audit this Next.js app for performance and RSC problems." is natural everyday phrasing for a coding assistant request and the README provides no explicit trigger boundaries, exclusions, or narrower activation conditions. In a markdown skill description, this can make it unclear when the skill should activate versus when a general assistant response would be more appropriate.

Content

No source excerpt is available for this finding.

Undeclared Tool Scope

Medium
Category
MCP Least Privilege
Confidence
70% confidence
Finding

Without declared permissions the skill's intent is opaque and cannot be validated.

Content

No source excerpt is available for this finding.

Vague Triggers

Medium
Category
Not specified by scanner
Confidence
87% confidence
Finding

The description lists many trigger-style phrases such as 'review/audit a Next.js app', 'find performance problems', and 'debug why a page isn't streaming' without defining boundaries or exclusions. While somewhat domain-specific, the activation guidance is still broad enough that ordinary Next.js help requests could invoke the skill unintentionally.

Content

No source excerpt is available for this finding.

External Transmission

Medium
Category
Data Exfiltration
Confidence
50% confidence
Finding

Data is being sent to an external URL. This could be legitimate telemetry or data exfiltration. Manual review is recommended.

Content

Scanner excerpt · examples/fixture/app/feed/page.tsx (reported line 5)May include surrounding context.

tsx
// and no metadata export. The scanner should flag `request-waterfall` (INFO)
// and `page-missing-metadata` (WARN).
export default async function FeedPage() {
  const user = await fetch("https://api.example.com/user").then((r) => r.json());
  const posts = await fetch("https://api.example.com/posts").then((r) => r.json());

  return (

External Transmission

Medium
Category
Data Exfiltration
Confidence
50% confidence
Finding

Data is being sent to an external URL. This could be legitimate telemetry or data exfiltration. Manual review is recommended.

Content

Scanner excerpt · examples/fixture/app/feed/page.tsx (reported line 6)May include surrounding context.

tsx
// and no metadata export. The scanner should flag `request-waterfall` (INFO)
// and `page-missing-metadata` (WARN).
export default async function FeedPage() {
  const user = await fetch("https://api.example.com/user").then((r) => r.json());
  const posts = await fetch("https://api.example.com/posts").then((r) => r.json());

  return (

Static analysis

No suspicious patterns detected.