vexctl is a command-line tool for creating, applying, and attesting VEX (Vulnerability Exploitability eXchange) data. It is built as a single binary using Cobra for CLI, with subcommands for creating VEX documents, merging them, filtering SARIF scanner results, generating attestations, and validating documents against the OpenVEX specification. The tool integrates with Sigstore for keyless signing and supports multiple VEX formats (OpenVEX native, CSAF, CycloneDX). It can attach VEX attestations to container images via OCI referrers API or legacy tag layout. The architecture follows a clean separation of concerns: CLI handlers in `internal/cmd/` delegate to a core library in `pkg/ctl/`, which uses an interface (`Implementation`) for testability. The `pkg/attestation/` package handles in-toto attestations and Sigstore signing independently. The codebase demonstrates strong engineering practices with dependency injection, options struct patterns, and comprehensive test data. While primarily an application, it also processes vulnerability data (SARIF, VEX documents) and includes validation logic that could be reused in other security tooling.