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mythos-agent

AI code-review assistant for application security.

Open-source. Reads your code, flags likely security issues, explains its reasoning, suggests fixes.

mythos-agent.com

Quick Start • How It Works • Commands • Hunt Mode • Variant Analysis • Integrations • Contributing • Vision • Roadmap

mythos-agent reviews your code the way a reviewer on a security-focused team would. It walks through likely issue patterns, checks for variants of known CVEs, ranks findings by confidence, and suggests fixes you can accept or reject. See VISION.md for the full framing.

For new contributors: the active 6-month working plan is in the pinned issue [Roadmap] mythos-agent H1 2026 Goals. Look for 🙋 markers to spot items where help is wanted. New here? See CONTRIBUTING.md for good-first-issue guidance.

For security teams and EU CRA-compliant downstream manufacturers: see SECURITY.md for our vulnerability disclosure SLAs, docs/security/cra-stance.md for our EU CRA role declaration, docs/security/threat-model.md for our public threat model, and RELEASES.md for our versioning, LTS, and EOL policy. OpenSSF Best Practices Badge (Passing) submission targeted June 2026; releases are signed via Sigstore and ship with CycloneDX SBOMs for downstream Manufacturer compliance.

npx mythos-agent hunt

🔐 mythos-agent hunt — AI Code-Review Assistant

✔ Phase 1: Reconnaissance — 12 entry points, express, typescript, postgresql
✔ Phase 2: Hypothesis — 8 security hypotheses generated
✔ Phase 3: Analysis — 15 findings (semgrep, gitleaks, trivy, built-in), 22 false positives dismissed
✔ Phase 4: Reproduction — 2 finding chains, 3 reproductions

🧪 Security Hypotheses

  [HIGH] HYPO-001 — Race condition: concurrent payment requests could double-charge
    src/payments.ts:45 (race-condition)
  [HIGH] HYPO-002 — Auth bypass: JWT token not validated after password change
    src/auth.ts:78 (auth-bypass)

📊 Confidence Summary

  3 confirmed | 8 likely | 4 possible | 22 dismissed

⛓️ FINDING CHAINS

 CRITICAL  SQL Injection → Auth Bypass → Data Exfiltration
  ├── src/api/search.ts:45      — unsanitized input in SQL query
  ├── src/middleware/auth.ts:88  — JWT verification skippable
  └── src/api/export.ts:23      — bulk export has no ACL

🧪 Reproductions

  SPX-0001 — SQL injection in search endpoint
    See repro steps in docs/reproductions/SPX-0001.md

  Trust Score: 2.3/10 — critical issues found

Quick Start

# Install
npm install -g mythos-agent

# Quick scan (no API key needed)
mythos-agent scan

# Full autonomous hunt (needs API key)
mythos-agent init
mythos-agent hunt

# Find variants of known CVEs
mythos-agent variants CVE-2021-44228

# Ask security questions
mythos-agent ask "are there any auth bypasses?"

# Check available tools
mythos-agent tools

How It Works

mythos-agent combines three things no other open-source tool does together:

1. Hypothesis-Driven Scanning

Instead of matching known patterns, the AI reasons about what COULD go wrong, generating hypotheses like "this transaction doesn't lock the row, potential race condition" or "this auth check uses string comparison, potential timing attack."

2. Variant Analysis (Big Sleep technique)

Given a known CVE, mythos-agent finds structurally similar but syntactically different code in your codebase. Same root cause, different location. This is how Google's Big Sleep found 20 real zero-days.

3. Multi-Stage Verification

Every finding goes through a confidence pipeline:

• Pattern scan → candidate
• AI hypothesis → theoretical risk confirmed
• Smart fuzzer → dynamically tested
• PoC generator → concrete exploit proves it's real

Only findings that survive multiple stages are reported as "confirmed."

Commands

Hunt Mode

mythos-agent hunt runs the full multi-agent pipeline:

┌──────────────┐     ┌──────────────┐     ┌──────────────┐     ┌──────────────┐
│    Recon     │ →   │  Hypothesis  │ →   │   Analyze    │ →   │   Exploit    │
│    Agent     │     │    Agent     │     │    Agent     │     │    Agent     │
├──────────────┤     ├──────────────┤     ├──────────────┤     ├──────────────┤
│ Map entry    │     │ Reason about │     │ All scanners │     │ Chain vulns  │
│ points, auth │     │ what could   │     │ + external   │     │ + generate   │
│ boundaries,  │     │ go wrong per │     │ tools + AI   │     │ PoC exploits │
│ data stores  │     │ function     │     │ verification │     │              │
└──────────────┘     └──────────────┘     └──────────────┘     └──────────────┘

Variant Analysis

Find code in your project that has the same root cause as known CVEs:

# Search for Log4Shell-like patterns
mythos-agent variants CVE-2021-44228

# Auto-detect and scan for variants
mythos-agent variants --auto

The variant analyzer extracts the root cause pattern from the CVE (not the surface syntax) and searches your codebase for structurally similar code.

Scanners (15 wired + 28 experimental, 329+ rules)

The Default scanners run on every mythos-agent scan. Experimental scanners are implemented + unit-tested classes that ship in the tarball but are not yet reachable from any CLI, HTTP, MCP, or agent entry point. They are tracked by KNOWN_EXPERIMENTAL in the wiring-invariant test.

Beyond the scanners above, mythos-agent ships complementary analyses (not counted in the scanner totals): call-graph + taint engine, DAST smart fuzzer, AI hypothesis agent, variant analysis, and git-history mining.

External tool integrations: Semgrep (30+ languages), Gitleaks (100+ patterns), Trivy (SCA + containers), Checkov (1000+ IaC policies), Nuclei (9000+ DAST templates)

Integrations

AI Providers

Pattern scanning, secrets, deps, and IaC work without any API key.

Comparison

This feature table is a capability comparison, not an accuracy claim. For reproducible, third-party-runnable accuracy numbers vs Semgrep CE / Snyk Code / CodeQL on OWASP Benchmark, CyberSecEval 3, Vul4J, and our CVE replay harness, see docs/benchmarks/external-scores.md.

Contributing

See CONTRIBUTING.md for details.

git clone https://github.com/mythos-agent/mythos-agent.git
cd mythos-agent && npm install && npm run build && npm test

Architecture

src/
  agents/         Multi-agent orchestrator + Recon/Hypothesis/Analyzer/Exploit agents
  analysis/       Code parser, call graph, taint engine, variant analyzer, service mapper
  agent/          AI integration, prompts, tools, fix validator
  cli/            44 CLI commands
  dast/           Smart fuzzer, PoC generator, payload library
  policy/         Policy engine + compliance mapping
  report/         Terminal, JSON, HTML, SARIF, dashboard
  rules/          Built-in + custom YAML + community registry
  scanner/        Pattern, secrets, deps, IaC, diff scanners
  store/          Results persistence + incremental cache
  tools/          External tool wrappers (Semgrep, Trivy, etc.)
vscode-extension/ VS Code extension
action/           GitHub Actions
bot/              PR Review Bot

License

MIT