Vyper Guard

Static security analyzer for Vyper smart contracts.

Vyper Guard scans .vy sources, runs a focused detector suite, and emits structured security reports for auditors, developers, and security teams. It is designed for fast local analysis with optional compiler-backed semantics and verification workflows.

Website: https://vyper-web.vercel.app

Who it is for

• Auditors and auditing companies
• Protocol and dApp developers
• Security and engineering teams

Primary use cases

• Pre-audit security scans
• CI security gates and regression checks
• Learning and reviewing Vyper security patterns

Features

• Vyper-focused static analysis for .vy contracts
• 22 built-in detectors (reentrancy, access control, external call safety, arithmetic risks, input validation, ERC-20 return handling)
• Always-on compiler advisories (compiler_version_check)
• Multiple report formats: CLI, JSON, Markdown, SARIF, HTML
• Verification workflows for unit and fuzz tests (verify, test, fuzz)
• Baseline suppression and baseline-diff for CI stability
• Optional remediation mode with tiered auto-fix controls
• Optional compiler-backed semantic mode (install vyper extra)
• CFG-aware CEI analysis plus cyclomatic complexity metrics in reports and stats
• Project-wide graph for directory scans (imports, interfaces, call/state maps)
• Explorer and on-chain analysis workflows (explorer, analyze-address)
• Deterministic priority scoring with governance notes and explicit fallback controls (--allow-ai-fallback)

Installation

Python 3.10+ is required.

pip install vyper-guard

Optional extras:

pip install vyper-guard[vyper]       # compiler-backed semantics
pip install vyper-guard[monitor]     # on-chain monitoring (web3 + aiohttp)
pip install vyper-guard[remediation] # GitHub remediation support
pip install vyper-guard[all]         # all optional features

Verify:

vyper-guard --version

Quickstart

Analyze a contract:

vyper-guard analyze contract.vy

Verify static analysis plus tests:

vyper-guard verify contract.vy --unit-cmd "pytest -q"

Generate a machine-readable report:

vyper-guard analyze contract.vy --format json --output report.json

Generate a SARIF report for code scanning:

vyper-guard analyze contract.vy --format sarif --output report.sarif

Generate an HTML report:

vyper-guard analyze contract.vy --format html --output report.html

Command guide (when to use)

Core commands

Verification (unit + fuzz)

Use verify for a single report that includes static findings plus unit/fuzz results. Use test or fuzz to run them independently.

vyper-guard verify contract.vy --unit-cmd "pytest -q"
vyper-guard fuzz contract.vy --fuzz-cmd "your-fuzz-command"

You can also set defaults via environment variables:

export GUARDIAN_UNIT_CMD="pytest -q"
export GUARDIAN_FUZZ_CMD="your-fuzz-command"

Configuration

Configuration is loaded in this order:

1. CLI flags
2. Environment variables
3. .guardianrc in the current directory (or .guardianrc.yaml, .guardianrc.yml)
4. ~/.guardianrc

Create a starter config:

vyper-guard init

Example verification config:

verification:
  unit_command: ["pytest", "-q"]
  fuzz_command: ["your-fuzz-command"]
  timeout_seconds: 600
  max_output_chars: 20000

Explorer and LLM keys are read from environment variables:

export GUARDIAN_EXPLORER_API_KEY="..."
export GUARDIAN_LLM_API_KEY="..."

Output formats

Use --format and --output for structured reports:

vyper-guard analyze contract.vy --format json --output report.json
vyper-guard analyze contract.vy --format sarif --output report.sarif
vyper-guard analyze contract.vy --format html --output report.html

Supported formats: cli, json, markdown, sarif, html.

Security scoring

Each run produces a score from 0 to 100 and a grade.

Base score is 100 with severity-based deductions:

• CRITICAL: -40 points (capped at -50)
• HIGH: -20 points (capped at -40)
• MEDIUM: -8 points (capped at -20)
• LOW: -3 points (capped at -10)
• INFO: -1 point (capped at -5)

Additional trust penalty:

• Detector runtime failures: -10 each (capped at -30)

Detector catalog

1. missing_nonreentrant
2. unsafe_raw_call
3. unchecked_send
4. missing_event_emission
5. timestamp_dependence
6. integer_overflow
7. unprotected_selfdestruct
8. dangerous_delegatecall
9. unprotected_state_change
10. send_in_loop
11. unchecked_subtraction
12. cei_violation
13. tx_origin_auth
14. missing_zero_address_check
15. weak_randomness
16. locked_ether
17. shadowed_state_variable
18. missing_input_validation
19. unsafe_assembly
20. missing_return_value
21. division_before_multiplication
22. incorrect_erc20_return

Compiler advisories are always evaluated and reported as compiler_version_check findings.

Remediation

Use remediation mode for guided fixes:

vyper-guard analyze contract.vy --fix

Limit remediation scope by risk tier:

vyper-guard analyze contract.vy --fix --max-auto-fix-tier B

Dry-run remediation:

vyper-guard analyze contract.vy --fix-dry-run --fix-report remediation-report.json

License

MIT. See LICENSE.

Disclaimer

Vyper Guard is a static analysis aid and does not guarantee absence of vulnerabilities. Use it together with manual review, testnet validation, and professional audits for high-value deployments.