Phy Bundle Size Audit

• Outcome: Pass
• Latest audit: Sep 12, 2026 · 5:04 AM UTC
• Version: 1.0.3

Overview

This skill is a coherent local bundle-analysis guide with some ordinary npm supply-chain caution points.

Before using the npm or npx examples, prefer project devDependencies with pinned versions, committed lockfiles, npm ci in CI, and least-privilege CI secrets. The local parsing snippets are consistent with the skill's bundle-audit purpose.

A.I.G

Vulnerability Patterns

• Insecure Dependencies: Introduces malicious components through unsafe dependency sources
• Skill Instruction Hijacking: Alters the agent's session goals or safety constraints when the skill loads
• Agent Memory Poisoning: Writes attacker-controlled rules into memory that affect later sessions
• Remote Payload Retrieval and Execution: Fetches external code whose behavior can change after review
• Embedded Malicious Code: Ships malicious scripts inside the skill and executes them locally

Findings (1)

T08 · Insecure Dependencies

Warning

• Location: SKILL.md:559

Finding

Unpinned npm Dependencies and Registry-Resolved npx Execution

Content

View full analysis

Vulnerability Details

File Location: SKILL.md, lines 559-560, 570, 592, 597, and 640-643
Vulnerability Type: Supply-chain exposure through unpinned package installation and execution
Risk Level: Medium

Vulnerable Code

bash

npm uninstall moment
npm install date-fns

bash

# OR install lodash-es: npm install lodash-es

bash

npx bundlesize

bash

npx size-limit

bash

npm install --save-dev webpack-bundle-analyzer

# Generate report
npx webpack-bundle-analyzer stats.json dist/ --no-open --report report.html

Technical Analysis

The Skill recommends installing npm packages without exact version constraints or documented integrity controls. It also invokes bundlesize and size-limit directly through npx.

When an explicitly pinned local dependency is unavailable, npx can resolve and download a package from the configured npm registry before executing its binary. Consequently, the code executed by these instructions is not fixed at Skill review time and may change as new package releases are published.

npm package installation may also execute package lifecycle scripts. A compromised package release, maintainer account, registry response, or transitive dependency could therefore introduce arbitrary code into the installation or execution process.

No package referenced by the Skill was demonstrated to be malicious. The vulnerability is the unsafe, mutable dependency execution pattern rather than evidence of an active malicious payload.

Attack Path

1. An attacker compromises a referenced package, one of its transitive dependencies, its maintainer account, or the registry path used by the environment.
2. The attacker publishes or serves a malicious package version.
3. A developer or CI pipeline follows the Skill's instructions and runs an unversioned npm install or npx command.
4. npm resolves the mutable package version from the r ...[truncated 920 chars]

Remediation

View remediation

Remediation Suggestions

1. Add required tools to the project's devDependencies using reviewed, exact versions rather than resolving the latest available releases at execution time:

   bash

   npm install --save-dev --save-exact bundlesize@VERSION size-limit@VERSION webpack-bundle-analyzer@VERSION
   

2. Pin optimization dependencies such as date-fns and lodash-es to reviewed versions where the instructions are intended for reproducible automation.

3. Commit package-lock.json and use:

   bash

   npm ci
   

   in CI to enforce lockfile-resolved versions and integrity hashes.

4. Prevent npx from downloading missing packages:

   bash

   npx --no-install bundlesize
   npx --no-install size-limit
   npx --no-install webpack-bundle-analyzer stats.json dist/ --no-open --report report.html
   

5. Prefer package scripts that execute lockfile-managed local binaries:

   json

   {
     "scripts": {
       "check:bundle": "bundlesize",
       "analyze:bundle": "webpack-bundle-analyzer stats.json dist/ --no-open --report report.html"
     }
   }
   

6. Review dependency changes and lockfile diffs, enable automated vulnerability monitoring, and restrict CI secrets and workflow-token permissions according to least privilege.

7. Where compatible with the required packages, disable unnecessary lifecycle scripts during installation or explicitly review packages that require them.

SkillSpector

Vulnerability Patterns

• Supply Chain: Unpinned Dependencies, External Script Fetching, Obfuscated Code
• Trigger Abuse: Overly Broad Trigger, Shadow Command Trigger, Keyword Baiting Trigger
• Prompt Injection: Instruction Override, Hidden Instructions, Exfiltration Commands
• Data Exfiltration: External Transmission, Env Variable Harvesting, File System Enumeration
• Privilege Escalation: Excessive Permissions, Sudo/Root Execution, Credential Access

Findings (4)

Vague Triggers

Medium

• Category: Not specified by scanner
• Confidence: 94% confidence

Finding

The trigger list includes generic phrases such as "reduce bundle size", "chunk size", "size limit", and "which package is largest" that could appear in ordinary conversation outside an explicit request to invoke this skill. The file provides examples but no negative examples or tighter activation constraints to distinguish when the skill should and should not activate.

Content

No source excerpt is available for this finding.

Rp1

Medium

• Category: MCP Rug Pull
• Confidence: 90% confidence

Finding

The skill instructs users to run npx bundlesize, which fetches and executes the latest package version at runtime unless a specific version is pinned. That creates a supply-chain risk: a compromised upstream package, typo-squatted resolution, or breaking release could execute unintended code in the developer or CI environment.

Content

No source excerpt is available for this finding.

Rp1

Medium

• Category: MCP Rug Pull
• Confidence: 90% confidence

Finding

The skill recommends npx size-limit without version pinning, so execution depends on whatever version is resolved at invocation time. In CI or local environments this can lead to arbitrary third-party code execution from an unexpected or compromised release, making it a classic supply-chain exposure.

Content

No source excerpt is available for this finding.

Rp1

Medium

• Category: MCP Rug Pull
• Confidence: 91% confidence

Finding

Using npx webpack-bundle-analyzer without an explicit version allows the latest package to be downloaded and executed on demand. Because this tool is intended for developer machines and CI, an upstream compromise or unexpected release could directly impact trusted build environments.

Content

No source excerpt is available for this finding.

Static analysis

No suspicious patterns detected.