A local-first security scanner with a browser UI. Scan your repo and triage in your browser, with no cloud and no account.

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Scan locally, browse locally

Nyx runs a cross-language taint analysis on your repository, then serves the results to a React UI bound to 127.0.0.1. You get a finding list with severity, evidence, and a step-by-step flow visualiser that walks the dataflow from source → sanitizer → sink. Triage decisions persist to .nyx/triage.json, which commits alongside your code so the team shares one triage state.

cargo install nyx-scanner
nyx scan           # runs the analyzer, caches findings in .nyx/
nyx serve          # opens http://localhost:9700 in your browser

Everything stays on your machine: loopback-only bind, host-header enforcement, CSRF on every mutation, no telemetry, no login.

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What's in the UI

Page	What it shows
Overview	Dashboard: finding counts by severity, top offenders, engine profile summary
Findings	Browsable list with severity badges, triage status, rule filter, language filter
Finding detail	Flow-path visualiser with numbered steps (source → sanitizer → sink), code snippets, evidence, cross-file markers, triage dropdown
Triage	Bulk update states (open, investigating, fixed, false_positive, accepted_risk, suppressed), audit trail, import/export JSON
Explorer	File tree with per-file symbol list and finding overlay
Scans	Run history, metrics, diff two scans to see what changed
Rules	Built-in and custom rules per language; add rules from the UI
Config	Live config editor; reload without restart

nyx serve flags: --port <N> (default 9700), --host <addr> (loopback only: 127.0.0.1, localhost, or ::1), --no-browser. See [server] in nyx.conf for persistent settings, and the Browser UI guide for the page-by-page UI tour and security model.

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CLI for CI

The same engine runs headless for CI pipelines. SARIF output uploads directly to GitHub Code Scanning.

# Fail the job on medium or higher, emit SARIF
nyx scan --format sarif --fail-on MEDIUM > results.sarif

# Ad-hoc JSON, no index
nyx scan ./server --format json --index off

# AST patterns only (fastest; skips CFG + taint)
nyx scan --mode ast

# Engine-depth shortcut: fast | balanced (default) | deep
# `deep` adds symex + demand-driven backwards taint for higher precision at ~2-3× cost
nyx scan --engine-profile deep

Forward cross-file taint runs in every profile. Symex and the demand-driven backwards walk are opt-in. Turn them on either via --engine-profile deep, or individually (--symex, --backwards-analysis). See the CLI reference for the full toggle matrix.

GitHub Action

- uses: elicpeter/nyx@v0.5.0
  with:
    format: sarif
    fail-on: MEDIUM
- uses: github/codeql-action/upload-sarif@v3
  with:
    sarif_file: nyx-results.sarif

Inputs: path, version, format (sarif|json|console), fail-on, args, token. Outputs: finding-count, sarif-file, exit-code, nyx-version. Linux and macOS runners (x86_64, ARM64).

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Install

Cargo (recommended):

cargo install nyx-scanner

Pre-built binaries: Grab the archive for your platform from Releases, verify against SHA256SUMS (and the detached SHA256SUMS.asc GPG signature, when present), unzip, and drop nyx on your PATH.

# Optional: verify the checksum file's GPG signature (when SHA256SUMS.asc is published)
gpg --verify SHA256SUMS.asc SHA256SUMS
sha256sum -c SHA256SUMS --ignore-missing
unzip nyx-x86_64-unknown-linux-gnu.zip && chmod +x nyx && sudo mv nyx /usr/local/bin/

From source:

git clone https://github.com/elicpeter/nyx.git
cd nyx && cargo build --release

Requires stable Rust 1.88+. The frontend is compiled and embedded in the binary at build time, so there is no separate install step for nyx serve.

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Languages

All 10 languages parse via tree-sitter and run through the full pipeline, but rule depth and engine coverage are uneven. Benchmark F1 on the 433-case corpus at tests/benchmark/ground_truth.json is 100% for nine of ten languages and 94.1% for Go, so F1 alone no longer separates the tiers. Tiering reflects rule depth, gated-sink coverage, and structural idioms the synthetic corpus does not fully stress:

Tier	Languages	F1	Use as a CI gate?
Stable	Python, JavaScript, TypeScript	100%	Yes
Beta	Java, PHP, Ruby, Rust, Go	94.1% to 100%	Yes, with light FP triage
Preview	C, C++	100% on synthetic corpus	No. STL container flow, builder chains, and inline class member functions are tracked, but deep pointer aliasing and function pointers are not. Pair with clang-tidy or Clang Static Analyzer

Aggregate rule-level F1: 99.3% (P=0.991, R=0.995). The single open FN is cve-go-2023-3188-vulnerable (owncast SSRF); the two open FPs (go-safe-007, go-safe-009) also sit on the Go side. Per-dimension detail and known blind spots live on the Language maturity page.

Validated against real CVEs

The corpus also holds a small set of vulnerable/patched pairs extracted from published advisories, so the benchmark floor is defended by regression protection on demonstrably real bugs rather than just synthetic analogues. Nyx fires on the vulnerable file and emits zero findings on the patched file for each pair.

CVE	Project	Language	Class
CVE-2023-48022	Ray	Python	Command injection
CVE-2017-18342	PyYAML	Python	Deserialization
CVE-2019-14939	mongo-express	JavaScript	Code execution (eval)
CVE-2025-64430	Parse Server	JavaScript	SSRF
CVE-2023-26159	follow-redirects	TypeScript	SSRF
CVE-2022-30323	hashicorp/go-getter	Go	Command injection
CVE-2024-31450	owncast	Go	Path traversal
CVE-2015-7501	Apache Commons Collections	Java	Deserialization
CVE-2017-12629	Apache Solr	Java	Command injection
CVE-2013-0156	Ruby on Rails	Ruby	Deserialization
CVE-2020-8130	Rake	Ruby	Command injection
CVE-2017-9841	PHPUnit	PHP	Code execution (eval)
CVE-2018-15133	Laravel	PHP	Deserialization
CVE-2016-3714	ImageMagick (ImageTragick)	C	Command injection
CVE-2019-18634	sudo (pwfeedback)	C	Memory safety
CVE-2019-13132	ZeroMQ libzmq	C++	Memory safety
CVE-2022-1941	Protocol Buffers	C++	Memory safety

cve-go-2023-3188-vulnerable (owncast SSRF) ships in the corpus too but is currently a known FN; it will move into the table once the engine fires on it.

Fixtures live under tests/benchmark/cve_corpus/ with upstream attribution headers.

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How it works

Two passes over the filesystem, with an optional SQLite index to skip unchanged files:

1. Pass 1: parse each file via tree-sitter, build an intra-procedural CFG (petgraph), lower to pruned SSA (Cytron phi insertion over dominance frontiers), and export per-function summaries (source/sanitizer/sink caps, taint transforms, points-to, callees).
2. Summary merge: union all per-file summaries into a GlobalSummaries map.
3. Pass 2: re-analyze each file with cross-file context under bounded context sensitivity (k=1 inlining for intra-file callees, SCC fixpoint capped at 64 iterations, and summary fallback for callees above the inline body-size cap). A forward dataflow worklist propagates taint through the SSA lattice with guaranteed convergence. Call-graph SCCs iterate to fixed-point (within the cap) so mutually recursive functions get accurate summaries.
4. Rank, dedupe, emit: findings are scored by severity × evidence strength × source-kind exploitability, then emitted to console, JSON, or SARIF.

Detector families: taint (cross-file source→sink), CFG structural (auth gaps, unguarded sinks, resource leaks), state model (use-after-close, double-close, must-leak, unauthed-access), AST patterns (tree-sitter structural match). Full detector docs: Detectors.

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Configuration

Config merges nyx.conf (defaults) and nyx.local (your overrides) from the platform config directory (~/.config/nyx/ on Linux, ~/Library/Application Support/nyx/ on macOS, %APPDATA%\elicpeter\nyx\config\ on Windows).

[scanner]
mode         = "full"        # full | ast | cfg | taint
min_severity = "Medium"

[server]
host = "127.0.0.1"
port = 9700
open_browser = true

# Project-specific sanitizer
[[analysis.languages.javascript.rules]]
matchers = ["escapeHtml"]
kind     = "sanitizer"
cap      = "html_escape"

Or add rules interactively: nyx config add-rule --lang javascript --matcher escapeHtml --kind sanitizer --cap html_escape. Caps: env_var, html_escape, shell_escape, url_encode, json_parse, file_io, fmt_string, sql_query, deserialize, ssrf, code_exec, crypto, unauthorized_id, all. Full schema: Configuration.

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Status

Under active development. APIs, detector behavior, and configuration options may change between releases. Rule-level F1 on the 433-case corpus is the CI regression floor; per-language detail lives in tests/benchmark/RESULTS.md.

Taint analysis is interprocedural. Persisted per-function SSA summaries carry per-return-path transforms and parameter-granularity points-to, and call-graph SCCs (including SCCs that span files) iterate to a joint fixed-point. The default balanced profile also runs k=1 context-sensitive inlining for intra-file callees. Symex (with cross-file and interprocedural frames) and the demand-driven backwards walk are opt-in. Enable them individually with --symex and --backwards-analysis, or together with --engine-profile deep.

Limitations:

• Interprocedural precision is bounded rather than unlimited. Context-sensitive inlining is k=1 with a callee body-size cap, and SCC fixed-point has an iteration cap. When the engine hits a bound it falls back to summaries and records an engine_note on the finding.
• Cross-language calls (FFI, subprocess, WASM) are not traversed. Each language is analysed independently.
• Several language features are not modeled: macros, most dynamic dispatch, aliased imports, reflection.
• C/C++ are preview tier. STL container flow, builder chains, and inline class member functions are tracked now; deep pointer aliasing and function pointers are not. A clean report should not be read as a clean audit. Pair with a clang-based tool before using as a hard CI gate.
• Results may contain false positives or false negatives; manual review is expected.

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Documentation

Browse the full docs site at elicpeter.github.io/nyx.

• Quick Start · CLI Reference · Installation
• nyx serve · Output Formats · Configuration
• How it works · Detectors (Taint, CFG, State, AST Patterns)
• Rule Reference · Language Maturity · Advanced Analysis · Auth Analysis

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Contributing

Contributions are welcome.

Nyx is open source and will always have a fully open-source core. To support long-term development and keep the project sustainable, contributors may be asked to sign a Contributor License Agreement before their first merged contribution.

Run sh scripts/check.sh before submitting. See CONTRIBUTING.md for the full guide, including how to add rules and support new languages. Open an issue for crashes, panics, or suspicious results; attach a minimal snippet and the Nyx version.

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AI Disclosure

• Engine code (taint, SSA, CFG, call graph, abstract interp, symbolic exec): predominantly human-written. AI was used selectively for refactors and boilerplate, with all merges human-reviewed.
• Docs and most of this README: AI-generated from the code and hand-edited. Report doc/code drift as a bug.
• Test fixtures and expected.yaml files: AI-assisted drafting, human-audited before landing.
• Frontend UI (React app): built with AI assistance, human-reviewed.

As with any static analyzer, validate findings against your own corpus before using Nyx as a CI gate.

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License

GNU General Public License v3.0 or later (GPL-3.0-or-later). The optional smt feature bundles Z3 (MIT-licensed); distributors of binaries built with --features smt should include Z3's license in their attribution. Full text in LICENSE; third-party dependencies in THIRDPARTY-LICENSES.html.