vulnerability-validation-skill AGENTS.md

A repository guide for finding and proving security vulnerabilities in source code. It explains how to test possible flaws with reachability checks, working proof-of-concept tests, negative controls, threat-model checks, and comparisons with fixed code.

In plain words
What is it for?
Use it to discover vulnerabilities in a target repository, rank candidates, validate reports or proof-of-concept code, and decide which findings are ready to report.
Why use it?
It prevents unverified scanner results or suspicions from being treated as real vulnerabilities without evidence.

Instructions file for CodexOpenCode

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.

agentmods
npx agentmods add instructions/omkhar/vulnerability-validation-skill/agents-md
Clone the repo
git clone --depth 1 https://github.com/omkhar/vulnerability-validation-skill

Made for: Codex, OpenCode.

Per session 2,535 This file is loaded in full into every session.
When invoked 2,535 The same file — it is already loaded in full.
Security scan A 0 findings. Scan, not verified.
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 $0.02535 $0.02535
Opus 5 $0.01267 $0.01267
Sonnet 5 $0.00507 $0.00507
Haiku 4.5 $0.00253 $0.00253

Measured 2d ago against content hash 69c8be9e02e6, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

vulnerability-validation-skill AGENTS.md 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 2d ago.

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.

AGENTS.md · 171 lines

How it starts

The opening of the file, as written. The whole thing — 171 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Repository Working Agreement

This repository packages one portable vulnerability-validation Agent Skill.

This skill discovers and validates vulnerabilities. Its default mode is native discovery: presented a target repository with no findings list (finding_source_type = native_discovery), it analyzes the code to find new vulnerabilities (0-days) itself, then drives every candidate through the existing validation machinery. A supplied scanner finding, researcher report, or PoC is an optional seed, not a prerequisite. Discovery is a gated precursor: it enumerates and ranks candidates but never dispositions a finding or computes severity at intake; only the existing validation gates (reachability, live PoC, negative control, threat-model fit, and fixed-build differential evidence) promote a candidate to a finding. The discovery methodology is mandated and documented in skill-core/references/discovery-intake.md; it is bounded by a declared stopping criterion, admits nothing to a maintainer without proof, and may never claim finding-space completeness. The canonical body stays a lean orchestration spine: discovery method detail lives in references, while scripts/discovery_engine.py may deterministically generate and rank candidate ledgers. The engine is a candidate source only: it cannot disposition findings, compute final severity, patch code, or produce maintainer-facing vulnerability claims.

A dev-only discovery-accuracy regression oracle (scripts/efficacy_oracle.py, fixtures under tests/eval/, methodology in docs/accuracy-eval-methodology.md) is permitted under this charter. It is a discrimination-regression measurement that runs the repository's existing deterministic gates over labeled SYNTHETIC fixtures to confirm they still block planted false positives, admit sound true positives, and protect discovery recall (no silent candidate drops, no false completeness claims); it encodes no real target or finding, and it generates and ranks no candidates itself.

A separate dev-only native candidate-generation oracle (scripts/discovery_engine_oracle.py, fixtures and baseline under tests/engine_eval/) may execute the real engine over pinned synthetic known-sink targets. It measures planted-target recall, cap survival, candidate burden, negative- control emissions, deterministic work units, and replay stability. These metrics are regression evidence for the committed heuristic corpus only, never real-world vulnerability recall, candidate validation, finding promotion, or finding-space completeness.

An autonomous discovery engine (scripts/discovery_engine.py) is also permitted under this charter. It inspects a local target repository, optionally provisions tools only into a run-local tool home, falls back to deterministic source heuristics when tools fail, and emits native discovery ledgers (discovery-plan.json, surface-inventory.json, discovery-lane-results.json, candidate-fusion.json). Its output is unvalidated candidate input for the existing gates, never a maintainer-ready report.

Read the full file on GitHub · 171 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. 2d ago First seen · 171 lines · 2,535 tokens per session scan A 69c8be9e02e6

Subscribe to this mod's changes

vulnerability-validation-skill AGENTS.md is an instructions file published in the GitHub repository omkhar/vulnerability-validation-skill (5 stars, last pushed 8d ago), licensed Apache-2.0. It adds 2,535 tokens to every session, about $0.0127 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 2026-08-31.

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