After a developer recently used Claude itself to discover that a Vercel plugin bundled with Claude Code was collecting bash commands and session data beyond its stated scope, the question of plugin supply-chain safety has moved from theoretical to immediate. This checklist gives you a practical process for auditing what your Claude Code plugins are actually doing.

Related news: Claude Code’s Vercel Plugin Quietly Collected Bash Commands — A Developer Used Claude to Expose It

Why Claude Code Plugins Are a Distinct Risk

In a traditional IDE, a plugin that misbehaves is annoying but usually contained. In Claude Code, plugins have access to the full context of an agentic session — including:

  • Terminal commands Claude is executing on your behalf
  • File system contents within your project (and potentially beyond)
  • Environment variables loaded into your shell
  • API keys and credentials that may appear in .env files or shell exports
  • Cross-project data if the plugin isn’t scoped to a single project

An agent running an autonomous multi-step workflow creates a much larger attack surface than a human clicking through IDE menus. Plugins that collect data silently have access to everything the agent sees.

The Audit Process

Step 1: List Your Installed Plugins

# List all Claude Code plugins currently installed
claude code plugins list

# Or inspect the plugins directory directly
ls ~/.claude/plugins/
ls ~/.config/claude/plugins/

For each plugin, note:

  • Plugin name and version
  • Source (official Claude Code plugins vs. third-party)
  • Last update date
  • What you originally installed it for

Step 2: Review Network Activity Per Plugin

Use a network monitor to observe what outbound connections your plugins are making:

# On Linux/macOS — watch outbound connections while Claude Code is running
sudo lsof -i -n -P | grep claude

# Or use netstat
netstat -an | grep ESTABLISHED

# More detailed — trace network calls for a specific process
# (replace <pid> with Claude Code's process ID)
strace -p <pid> -e trace=network 2>&1 | head -100

Flag any connections to:

  • Domains that don’t match the plugin’s stated purpose
  • Data analytics or telemetry endpoints
  • Unexpected third-party APIs

Step 3: Inspect Plugin Permissions

# Check what permissions a plugin requests
cat ~/.claude/plugins/<plugin-name>/manifest.json

# Or for npm-based plugins
cat ~/.claude/plugins/<plugin-name>/package.json

Look for permission scopes that exceed what the plugin needs:

  • filesystem: "*" when it only needs to read one config file
  • shell: true when it’s a UI-only plugin
  • env: true when it has no reason to access environment variables
  • network: "*" with no allowlist of permitted domains

Step 4: Check What Data Is Actually Transmitted

If a plugin makes outbound requests, inspect the payload:

# Use mitmproxy to intercept HTTPS traffic from Claude Code plugins
pip install mitmproxy
mitmproxy --mode transparent --ssl-insecure

# Set your system proxy to localhost:8080 and run Claude Code
# Review captured requests in the mitmproxy UI

Pay special attention to:

  • Whether bash command strings appear in request bodies
  • Whether file paths, filenames, or content are included
  • Whether session identifiers tie data back to your specific account

Step 5: Test Scope Creep

Create a test project that has no relationship to the plugin’s stated purpose. For example, if you have a Vercel plugin, create a plain Python project:

mkdir /tmp/test-python-project
cd /tmp/test-python-project
echo "print('hello')" > main.py

Open Claude Code in this project and perform normal development activities. Monitor whether the plugin activates, transmits data, or triggers consent dialogs — none of which should happen for an out-of-scope project.

The Safety Checklist

Before keeping or installing any Claude Code plugin, verify:

  • Minimal permissions — the plugin requests only the permissions needed for its stated function
  • Scoped to project — the plugin does not activate in unrelated projects
  • Clear opt-in — any data collection requires explicit, informed consent (not buried in an installation flow)
  • Disclosed endpoints — the plugin’s documentation lists every endpoint it communicates with
  • Known provenance — you can identify who published the plugin and review their privacy policy
  • Active maintenance — the plugin is actively maintained, not abandoned with unpatched vulnerabilities
  • Network audit passed — you’ve verified outbound connections match the stated purpose
  • No credential access — the plugin has no reason to read environment variables containing API keys

Removing Problematic Plugins

If a plugin fails the checklist:

# Remove via Claude Code CLI
claude code plugins remove <plugin-name>

# Or delete directly
rm -rf ~/.claude/plugins/<plugin-name>

# Clear any cached plugin data
rm -rf ~/.claude/plugin-cache/

After removing, restart Claude Code and verify the plugin no longer appears in your list.

Going Forward: Treating Plugins Like npm Dependencies

The Claude Code plugin ecosystem is still young, and the same supply-chain hygiene lessons learned from npm apply directly here:

  1. Don’t install plugins you don’t need — minimum footprint reduces risk
  2. Pin versions — avoid auto-updates that could change plugin behavior without your review
  3. Review changelogs before updating — check what changed, not just that a new version exists
  4. Run sensitive work in minimal environments — consider a Claude Code profile or separate install with no plugins for security-sensitive tasks

The Vercel incident is a reminder that “installed as a convenience” is how supply-chain compromises typically begin. Agentic AI tools have more context than a typical IDE plugin — and that makes the stakes higher.

Sources

  1. TechRadar — “Dev uses Claude to expose why a popular no-code platform wants to read all your prompts”
  2. OWASP Top 10 for Agentic Applications
  3. Claude Code Plugin Documentation

Researched by Searcher → Analyzed by Analyst → Written by Writer Agent (Sonnet 4.6). Full pipeline log: subagentic-20260413-2000

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