VexHub

Status: Implemented Source: src/VexHub/ Owner: VEX Guild

Purpose

VexHub aggregates, validates, and distributes VEX statements from multiple upstream sources. It is the canonical VEX distribution layer for Stella Ops, providing deterministic outputs, conflict detection, and offline-friendly operation for internal services (such as VexLens) and external tools (Trivy/Grype).

Quick Links

Architecture
VexLens (consumer / consensus)
Excititor (ingestion projection)
IssuerDirectory (issuer trust)

Components

Services:

StellaOps.VexHub.WebService - Minimal API host for distribution endpoints, the admin conflict-resolution endpoint, health probes, rate limiting, and Router registration

There is no StellaOps.VexHub.Worker project. A background ingestion scheduler (VexIngestionScheduler) is implemented in StellaOps.VexHub.Core but is not wired into the WebService host. In production, scheduled ingestion is handled by the Excititor Worker, which projects AOC-checked claims into vexhub.statements.

Libraries:

StellaOps.VexHub.Core - Normalization pipeline, schema validators (OpenVEX/CycloneDX/CSAF), signature verifier, statement flagging, export service, ingestion service
StellaOps.VexHub.Persistence - PostgreSQL data source, repositories, and embedded SQL migrations (schema vexhub)

Configuration

Settings bind from the VexHub section (VexHubOptions); PostgreSQL binds from Postgres. Key groups:

PostgreSQL connection (schema: vexhub); migrations auto-apply on startup via AddStartupMigrations
Top-level scalars: EnableSignatureVerification (default true), RequireSignedStatements (default false), StaleDataThresholdDays (default 90, drives statement flagging; 0 disables), plus page-size and polling defaults (DefaultApiPageSize, MaxApiPageSize, DefaultPollingIntervalSeconds, MaxConcurrentPolls)
SignatureTrustRoots (map of signing-key fingerprint -> trusted DSSE HMAC root; empty means signed VEX fails closed as unavailable)
Ingestion (EnableDeduplication, EnableConflictDetection, BatchSize, FetchTimeoutSeconds, MaxRetries)
Distribution (EnableBulkExport, EnableWebhooks, CacheDurationSeconds, RateLimitPerMinute)
SourceBackoff (exponential backoff for source polling failures: InitialBackoffSeconds, MaxBackoffSeconds, BackoffMultiplier, JitterFactor, MaxConsecutiveFailures)
ApiKeys (external tool API keys; presented via X-Api-Key header or api_key query param)

API Surface

Read endpoints require scope vexhub:read; the conflict-resolution endpoint requires vexhub:admin.

GET /api/v1/vex/cve/{cveId} - Query VEX statements by CVE (limit/offset)
GET /api/v1/vex/package/{purl} - Query VEX statements by PURL (URL-decoded)
GET /api/v1/vex/source/{sourceId} - Query statements from a specific source
GET /api/v1/vex/statement/{id:guid} - Single statement by id
GET /api/v1/vex/search - Filtered search (sourceId, vulnerabilityId, productKey, status, isFlagged, plus limit/offset); status accepts affected / fixed / not_affected / under_investigation
GET /api/v1/vex/stats - Dashboard statistics: totalStatements, verifiedStatements, flaggedStatements, byStatus, bySource (bucketed by issuer category), recentActivity (last 20), and a 7-day trends window
GET /api/v1/vex/export - Bulk OpenVEX feed (application/vnd.openvex+json)
GET /api/v1/vex/index - JSON index manifest (version, lastUpdated, endpoints) advertising the by-CVE/by-package/by-source/search/stats/export routes (response body, not a static file)
POST /api/v1/vex/conflicts/resolve - Resolve open conflicts for a vulnerability-product pair (admin; audited). Body: { cveId, selectedStatementId, resolutionType, notes? }. resolutionType=defer records the conflicts as suppressed with no winning statement; any other value marks them manually_resolved with the selected statement as winner. Returns 204 (or 400/404 on validation/no-open-conflicts).
GET /health, /health/liveness, /health/readiness - anonymous probes (return { status, service })

Statements carry a SHA-256 content_digest for dedup; timestamps are UTC.

Rate limiting (sliding 1-minute window) is applied per client (API-key id, else forwarded/remote IP); /health* is exempt. Responses carry X-RateLimit-Limit / X-RateLimit-Remaining / X-RateLimit-Reset headers, and exceeded limits return 429 with Retry-After. Authenticated clients receive 2x the configured Distribution.RateLimitPerMinute.

Dependencies

PostgreSQL (schema: vexhub with tables: sources, statements, conflicts, provenance, ingestion_jobs, webhook_subscriptions; no export_cursor / no tenant_id — statements are global)
Authority (bearer-token authentication; scopes vexhub:read / vexhub:admin)
VexLens (consumes VexHub statements/provenance; hosts the consensus endpoint)
Excititor Worker (projects AOC-checked VEX claims into vexhub.statements)

Architecture: ./architecture.md
VexLens: ../vex-lens/
IssuerDirectory: ../issuer-directory/
Excititor: ../excititor/

Current Status

WebService implemented with the distribution API, admin conflict-resolution endpoint, API-key + bearer auth, in-process rate limiting, and startup migrations. Normalization, validation (OpenVEX/CycloneDX/CSAF), offline DSSE-HMAC signature verification, and OpenVEX export are in place. Scheduled ingestion is not run by a VexHub worker (none exists); statements are populated by the Excititor Worker’s projection into vexhub.statements. Prometheus metrics and dedicated tracing spans are not yet implemented (roadmap).