vulnerability-writeup

vulnerability-writeup is a skill for Claude Code, Codex from bex-co/bex-security. It costs 54 tokens per session (4,964 once invoked), scanned A, original, Apache-2.0.

A guide for turning security findings, vulnerability notes, proof-of-concept code, or scan results into a clear vulnerability report. It treats the initial finding as a claim to validate rather than as a confirmed security flaw.

In plain words
What is it for?
Use it to investigate one vulnerability or a disclosure campaign and produce a self-contained report that another security researcher can understand and reproduce safely.
Why use it?
It helps prevent overstated reports by checking the software version, attacker access, entry point, expected behaviour, actual failure, and demonstrated impact.

Skill for Claude CodeCodex

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 skills/bex-co/bex-security/vulnerability-writeup
Any agent
npx skills add bex-co/bex-security --skill vulnerability-writeup
Clone the repo
git clone --depth 1 https://github.com/bex-co/bex-security

Made for: Claude Code, Codex.

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 vulnerability-writeup

README.md
[![agentmods](https://agentmods.dev/badge/skills/bex-co/bex-security/vulnerability-writeup.svg)](https://agentmods.dev/skills/bex-co/bex-security/vulnerability-writeup)
Your own site
<a href="https://agentmods.dev/skills/bex-co/bex-security/vulnerability-writeup"><img src="https://agentmods.dev/badge/skills/bex-co/bex-security/vulnerability-writeup.svg" alt="Measured on agentmods" height="20"></a>
Per session 54 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 4,964 The whole file, excluding the scripts and references it only reads on demand.
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 $0.00054 $0.04964
Opus 5 $0.00027 $0.02482
Sonnet 5 $0.00011 $0.00993
Haiku 4.5 $0.00005 $0.00496

Measured 3d ago against content hash 78105d91972d, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

vulnerability-writeup 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.

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.

plugins/codex-security/skills/vulnerability-writeup/SKILL.md · 183 lines

How it starts

The opening of the file, as written. The whole thing — 183 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Vulnerability Writeup

Purpose

Produce a disclosure report that another security researcher can understand, check and, where safely possible, reproduce. Treat the original finding as a hypothesis, not a conclusion. Establish the assessed software version, attacker position, reachable entry point, expected security behaviour, actual failure and narrowest demonstrated impact before deciding how strongly the report can speak. Pin the exact underlying source privately so the report remains accurate without burdening the reader with unnecessary commit hashes.

The result is still a finished, distributable vulnerability report, not an interactive review. Bring the scepticism, evidence discipline and approachable researcher-to-researcher voice of a good conversational review into the report itself.

Accept supplied notes, disclosure documents, existing reports, PoCs, source trees and scanner findings as first-class inputs. Do not require a scan ID, finding bundle, manifest, coverage receipt or other Codex Security scan artefact.

Non-negotiable rules

  • Give each distinct vulnerability its own report directory and exactly one drafting sub-agent. The main agent owns inventory, deduplication, source checks and final acceptance.
  • During Codex Security final reporting, the scan request authorises those one-finding drafting sub-agents. Do not request separate delegation approval.
  • When the exact vulnerable source revision is available, inspect it. Resolve the complete commit internally when possible and note dirty, shallow, missing, patched or mismatched source. For a reproduced vendor or distribution package, verify every reader-facing excerpt and line citation against that exact patched source; use upstream source separately for history unless it is also the code that ran. Follow relevant dependency code in causal order and identify its exact tested version. Use git show REV:PATH for a non-checked-out revision rather than treating the current worktree as that revision. In the report, identify the software by its verified public release whenever one exists.
  • If the exact source or revision is unavailable, stop and request it. Produce a report-only assessment only when the user explicitly accepts that limitation, and make every source-dependent conclusion visibly conditional.
  • When source and release history are available, trace the vulnerable code back to the change that introduced it and determine which released versions actually contain the vulnerable behaviour. Inspect the relevant tags, release branches, fixes and backports; never turn an unverified commit range into an affected-version claim.
  • Never invent a source excerpt, line number, revision, affected version, first affected release, fixed release, advisory, CVE, CVSS vector, deployment prevalence, exploit route, execution result or observation.
  • Distinguish source evidence, inspected-but-unexecuted PoCs, actual runtime observations, supplied report claims, inference and unknowns. Do not promote an inspected PoC into a reproduced vulnerability.
  • Do not use "witness" as shorthand for supporting evidence. Name the actual source excerpt, test input, HTTP request and response, execution trace, proof-of-concept run, observed output or counterexample, and explain exactly what it demonstrates. Preserve an actual source identifier containing that word only when necessary, and immediately explain its concrete meaning.
  • Test only within the user's explicit authorisation. Use disposable local targets for crashing, destructive or privilege-escalating PoCs. Never contact or test a public, external or production target without target-specific permission.
  • Do not manufacture PoC commands, logs, screenshots or sample output. Include observed output only when it was actually produced or when a supplied, identifiable trace was inspected. Label a prediction as expected output and explain that it was not observed.
  • Write in the language and locale the user requests; when they do not specify one, use their normal default. Be warm, direct and exact; guide substantive reasoning with a natural we, and use I only for work actually performed. Describe what the software should do, what it actually does and why that matters in plain language.
  • Give people clear, conventional names when they help explain the finding: Alice is the legitimate account or resource owner, Bob is another legitimate user or intended recipient, Mallory is the active attacker, and Eve is a passive observer. Use matching example usernames such as alice, bob, mallory and eve consistently in prose, commands and PoCs.
  • Make every delivered report and PoC portable and self-contained. Use repository-relative source paths, report-relative commands and verified software versions. Never include an author-machine-specific absolute path in report prose, excerpts, citations, links, PoC code, build files, command examples or captured output; retain a verified absolute target-system path when it is necessary to describe or reproduce the vulnerability.

Read the full file on GitHub · 183 lines

Files

What ships with it

2 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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 · 183 lines · 54 tokens per session scan A 78105d91972d

Subscribe to this mod's changes

vulnerability-writeup is a skill published in the GitHub repository bex-co/bex-security (40 stars, last pushed 4d ago), licensed Apache-2.0. It adds 54 tokens to every session and 4,964 once invoked, about $0.0003 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 2026-08-30.

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