vex

vex is a skill for Claude Code from microsoft/hve-core. It costs 31 tokens per session (1,385 once invoked), scanned A, original, MIT.

A reference and set of procedures for VEX documents. VEX, or Vulnerability Exploitability eXchange, records whether reported software vulnerabilities affect a product and why.

In plain words
What is it for?
It is for setting up VEX files and workflows, documenting vulnerability status, and reviewing security evidence.
Why use it?
It provides a consistent way to create, review, validate, and attest vulnerability decisions alongside software bills of materials.

Skill for Claude Code ✓ vendor

Written for Claude Code: user-invocable in frontmatter. Also seen: mentions subagents.

Good fit It is for setting up VEX files and workflows, documenting vulnerability status, and reviewing security evidence.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/microsoft/hve-core/vex
About the project

HVE Core is a collection of agents, prompts, coding instructions, and skills for building repeatable software-development workflows with GitHub Copilot. It is intended for individuals and teams that want structured AI-assisted research, planning, implementation, and review, while the catalogue entries provide many of its reusable workflow components.

microsoft/hve-core · 1,436 stars · on GitHub

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add microsoft/hve-core --skill vex
Clone the repo
git clone --depth 1 https://github.com/microsoft/hve-core

Made for: Claude Code.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for vex

README.md
[![agentmods](https://agentmods.dev/badge/skills/microsoft/hve-core/vex.svg)](https://agentmods.dev/skills/microsoft/hve-core/vex)
Your own site
<a href="https://agentmods.dev/skills/microsoft/hve-core/vex"><img src="https://agentmods.dev/badge/skills/microsoft/hve-core/vex.svg" alt="Measured on agentmods" height="20"></a>
Per session 31 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,385 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00031 $0.01385
Opus 5 $0.00015 $0.00692
Sonnet 5 $0.00006 $0.00277
Haiku 4.5 $0.00003 $0.00138

Measured 3d ago against content hash e4590ad74ba3, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-07, from the pricing page.

Security

Grade A, and why

vex scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 3d ago.

The scan reads SKILL.md. This mod also ships 3 executable files (scripts/vex_gate.py, tests/fuzz_harness.py, tests/test_vex_gate.py), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

.github/skills/security/vex/SKILL.md · 113 lines

How it starts

The opening of the file, as written. The whole thing — 113 lines — stays where its author put it; the contents beside it link to each section on GitHub.

VEX skill

This skill is the entrypoint for VEX operations in hve-core. It combines the OpenVEX v0.2.0 specification reference with reusable management playbooks for implementing, reviewing, and validating VEX documents. The normative reference material below remains the authoritative source for schema, status logic, and public-source guidance.

VEX management playbooks

Detection, drafting, and attestation are workflow-owned automation. This skill supplies the reusable procedures, mutation rules, and review criteria. The CVE Analyzer subagent performs the per-CVE exploitability analysis that feeds those workflows.

Implement VEX in a target project

Use this playbook when standing up VEX in a target project. Scaffold the VEX document under security/vex, wire the vex-detect and vex-draft workflows, reference the PR-body scaffold in assets/pr-body-scaffold.yml, connect the dedicated reusable VEX attestation workflow for provenance and OpenVEX-over-SBOM attestation, and set CODEOWNERS on the VEX document. Use references/vex-status-logic.md and the vex-standards.instructions.md instructions for the detailed rules.

Review and validate VEX

Use this playbook when reviewing drafted VEX statements. Assess the status determination against the evidence and confidence bands, honor the document mutation and forbidden-transition contract, and validate the release attestation output. Attestation generation is owned by the dedicated reusable VEX attestation workflow, not by the reviewer. The forthcoming tested gate module and tests will live in this skill so the workflow and interactive entry points can share the same rules.

VEX statuses

Status Meaning
not_affected The vulnerability is not exploitable in this product. Requires a justification or impact_statement.
affected The vulnerability is exploitable. Requires an action_statement describing remediation.
fixed The vulnerability was present but has been remediated in this product version.
under_investigation The author is evaluating whether the vulnerability affects this product. Safe default for uncertain cases.

Read the full file on GitHub · 113 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 3d ago First seen · 113 lines · 31 tokens per session scan A e4590ad74ba3

Subscribe to this mod's changes

vex is a skill published in the GitHub repository microsoft/hve-core (1,436 stars, last pushed today), licensed MIT. It adds 31 tokens to every session and 1,385 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-03.

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