vibecheck

A fast, agent-native "safe to ship?" gate for vibe-coded apps. It parses your JS/TS/JSX/TSX (@babel/parser), Python (the stdlib ast), and Go (go/parser) with real parsers and uses taint analysis (inter-procedural for JS/TS, Python, and Go — return-taint + param→sink summaries, within a file and across files) to flag the security classes AI coding agents get wrong — committed secrets, SQL injection through abstracted raw-query APIs, XSS, SSRF, path traversal, command injection, insecure deserialization, weak JWT/CORS/cookies — and ranks every finding by confidence so an agent can fix the real ones and ignore the noise.

vibecheck .          # human report (severity + confidence)
vibecheck . --ci     # exit 1 only on high-confidence (taint-backed) issues
vibecheck . --json   # machine-readable findings for agents / CI

What it is — and what it is not (read this)

vibecheck is not a replacement for Semgrep or CodeQL. Those are deeper, broader, multi-language engines and you should run them for full coverage. vibecheck aims to be better on one narrow, measurable axis: a low-false-positive, taint-backed gate for the AI-vibe-coding failure classes that runs inside agent loops and pre-commit in milliseconds, with published precision/recall so you can trust the --ci/MCP signal. Use it alongside the big engines, not instead of them.

| | vibecheck | Semgrep | CodeQL | |--|--|--|--| | Parsing | real AST (Babel JS/TS/JSX + Python ast) | real, many langs | real, many langs | | Data-flow | inter-procedural (return-taint + param→sink; intra-file + cross-file by import) | taint (Pro) | full inter-procedural | | Languages | JS/TS/JSX/TSX + Python + Go | many | many | | Speed / infra | ms, local, no account | fast | slower, CI-oriented | | Agent-native (MCP, confidence gating) | yes, first-class | partial | no | | Breadth of rules | small, focused | 2000+ | huge |

If you only adopt one general SAST, adopt Semgrep or CodeQL. Adopt vibecheck as the fast agent/CI pre-flight that won't drown an agent in false positives.

Measured quality (not claimed)

Against a labeled benchmark of 91 cases across JS/TS, Python and Go (vulnerable + safe + deliberately tricky-safe), the core detectors score (see METRICS.md, reproduce with bun benchmark/run.ts):

• Precision 100%, Recall 100%, F1 100% on the corpus.

The tricky-safe cases that produce zero false positives include: parameterized queries, tagged- template SQL, numeric-coerced and schema-validated input, ORM/RegExp .exec(), Supabase anon / Stripe publishable keys, hardened cookies, allow-listed CORS, and pinned JWT algorithms — exactly the patterns a regex linter trips on. This benchmark is curated; for a real-world measurement (9 pinned OSS repos, 1,218 files, manually triaged), see docs/CORPUS.md — which exposed a critical bug (Python/Go files weren't being scanned in real scans) and drove precision fixes (relative redirects, server-source-only SSRF).

Confidence

Every finding has a confidence:

• high — a user-input source provably flows into the sink (taint-backed), or a deterministic fact (committed secret, JWT none). These fail --ci and are what the MCP scan tool returns by default.
• medium — a dangerous sink on a non-literal value with no proven source (e.g. eval(x)).
• review — a structural smell that needs a human (e.g. a route with no visible auth). Excluded from --ci and from the agent loop by default, so agents never chase phantom work. Add --all to include them.

Install & use

npm i -D @arisrhiannon/vibecheck    # or: bun add -d @arisrhiannon/vibecheck (Node >= 20)
vibecheck . --ci
vibecheck explain VC-SQLI
vibecheck mcp           # MCP stdio server exposing a `scan` tool (high-confidence by default)

Agents: see AGENTS.md — run vibecheck . --ci before declaring a task done and fix every high-confidence finding.

JS/TS scanning needs nothing extra. Python scanning requires python3 on PATH; Go scanning requires a go toolchain on PATH (the analyzer is compiled once and cached). If a runtime is absent those files are skipped; if an analyzer fails, a warning is printed to stderr (so a crash never silently drops findings).

Rules (implemented + benchmarked)

Taint-backed: VC-RCE-EVAL, VC-RCE-CHILD-PROCESS, VC-SQLI, VC-XSS-REACT, VC-XSS-DOM, VC-SSRF, VC-PATH-TRAVERSAL, VC-OPEN-REDIRECT. AST config: VC-CORS-WILDCARD, VC-JWT-NONE, VC-JWT-UNPINNED, VC-COOKIE-INSECURE, VC-STACK-EXPOSURE. Provenance/secrets: VC-SECRET-* (8), VC-ENV-COMMITTED/DRIFT/MISSING, VC-NEXT-PUBLIC-SECRET, VC-SUPABASE-SERVICE-ROLE. Advisory: VC-ROUTE-NO-AUTH (review), VC-INPUT-NO-VALIDATION. Python (VC-PY-*): VC-PY-RCE, VC-PY-CMDI, VC-PY-SQLI, VC-PY-DESERIALIZE, VC-PY-YAML, VC-PY-SSTI, VC-PY-OPEN-REDIRECT, VC-PY-PATH. Go (VC-GO-*): VC-GO-CMDI, VC-GO-SQLI, VC-GO-PATH, VC-GO-OPEN-REDIRECT, VC-GO-SSRF. vibecheck explain <id> prints the fix for each.

Limitations

• JS/TS/JSX/TSX + Python + Go (Python needs python3, Go needs a go toolchain on PATH). More languages are roadmap (each via its own real parser, never hand-rolled).
• Taint scope: JS/TS taint is inter-procedural with real cross-file module resolution — function summaries carry return-taint and parameter→sink reachability, resolved within a file and across files via resolved relative imports (named, aliased a as b, and namespace * as ns), propagated multi-hop by a fixpoint; sanitizers respected. Not tracked (false negatives): re-exports (export { x } from …), default exports, CommonJS require/dynamic import(), bare/package imports, chains deeper than ~7 hops in worst-case file order, methods, and destructured params. Python is also inter-procedural (return-taint + param→sink and class @staticmethod resolution, intra-file and cross-file via resolved from .mod import/ import mod; not resolved: import a.b dotted-unaliased, */re-exports, decorators). Python request sources span Flask, Django, aiohttp (request.match_info, await request.post()), FastAPI/ Starlette (request.query_params/path_params, await request.json()/form()), Tornado, Bottle, Pyramid. Go is inter-procedural within and across packages (return-taint + param→sink; unaliased pkg.Func resolves by package name). Aliased package imports (import u "…/util") and multi-return assignments (x, _ := f(src)) are not tracked.
• Config/secret rules are pattern-based where AST adds no value.
• A high-signal gate and early-warning — not a proof of security. Pair it with Semgrep/CodeQL and review.

Config — .vibecheck.json

{ "ignoreRules": ["VC-INPUT-NO-VALIDATION"], "allowPaths": ["test/**"], "failSeverity": "high" }

License

MIT © 2026 Aris Rhiannon — see LICENSE.