What is cve-zero-day-scanner?

A workflow for checking software dependencies, container base images, operating-system packages, infrastructure providers, plugins, and agent tools for current security vulnerabilities. CVEs are publicly tracked vulnerability records, while a zero-day is a newly exploited or not-yet-fixed security flaw.

Use it before releases, after dependency changes, during security incidents, or on a schedule for long-running services. It helps inventory exact versions, query advisory sources, assess exposure, and document fixes.

It shows which known vulnerabilities affect a specific build and whether attackers are actively exploiting them, instead of relying only on old update checks or severity scores. It also records evidence and helps turn findings into owned patch plans.

cve-zero-day-scanner — Skill for Codex by ashermahonin

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 ashermahonin/agentic-skills --skill cve-zero-day-scanner

Clone the repo

git clone --depth 1 https://github.com/ashermahonin/agentic-skills

Made for: 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.

README.md

[![agentmods](https://agentmods.dev/badge/skills/ashermahonin/agentic-skills/cve-zero-day-scanner/github.svg)](https://agentmods.dev/skills/ashermahonin/agentic-skills/cve-zero-day-scanner)

Your own site

<a href="https://agentmods.dev/skills/ashermahonin/agentic-skills/cve-zero-day-scanner"><img src="https://agentmods.dev/badge/skills/ashermahonin/agentic-skills/cve-zero-day-scanner/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

Your own site · 80×15

<a href="https://agentmods.dev/skills/ashermahonin/agentic-skills/cve-zero-day-scanner"><img src="https://agentmods.dev/badge/skills/ashermahonin/agentic-skills/cve-zero-day-scanner.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 75 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 823 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.

Model	Per session	Once invoked
Fable 5.1	$0.00075	$0.00823
Opus 5	$0.00037	$0.00411
Sonnet 5	$0.00015	$0.00165
Haiku 4.5	$0.00007	$0.00082

Measured 12d ago against content hash 558a6b79065a, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-12, from the pricing page.

Security

Grade A, and why

cve-zero-day-scanner 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 12d 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.

agentic/skills/cve-zero-day-scanner/SKILL.md · 59 lines

How it starts

The opening of the file, as written. The whole thing — 59 lines — stays where its author put it; the contents beside it link to each section on GitHub.

CVE / Zero-Day Scanner

Purpose

Move from "we updated deps last quarter" to "as of today, these CVEs apply to this build, this one is on the KEV list, here is the patch plan and the owner". Treat unknown-unknowns by checking active exploitation feeds, not only static CVSS.

Scope and evidence

Read references/cve-workflow.md.
Pull the dependency graph: language lock files, container base images, OS packages, runtime versions, infra provider versions, MCP servers, plugins, model versions.
Pull the platform matrix from platform-detector and the OWASP status from security-owasp-web/-llm/-agentic.
Use Context7 MCP to verify current source documentation and query formats for CISA KEV, NVD, GitHub Security Advisories, ecosystem advisories, distro trackers, and vendor PSIRTs. Then query the live feeds/APIs/tools directly and record source URL, timestamp, parameters, result IDs, and raw evidence path.

Assessment

Build the asset inventory: every dependency, image, OS package, infra provider, plugin, and model with its pinned version.
Query advisory sources for each asset; collect candidate CVEs.
For each candidate CVE, compute: exposure path (is the vulnerable code path reachable?), severity (CVSS), exploitability (KEV listing, public PoC, exploit kit), blast radius, fix availability.
Bucket findings: Critical-now (KEV + reachable), Critical-latent (KEV but not reachable), High (CVSS ≥ 7 + reachable), Medium, Low.
Cross-check supply chain: signed artifacts, SLSA level, dependency confusion risk, typo-squat candidates near recent installs.
Produce patch plan: per finding, action (upgrade, pin, replace, mitigate-in-config, accept-risk-with-expiry), owner, ETA.
Issue release-gate verdict: Go / Conditional / Hold.

Safety rules

Use Context7 MCP every run for source/API documentation, but never treat Context7 output as the vulnerability feed itself.
Keep a decision trace: source feeds queried, query date/time, query parameters, response evidence, false-positive notes, accepted-risk register with expiry.
Refuse to mark a CVE Resolved without naming the artifact hash or version that contains the fix.
Escalate any KEV-listed vulnerability before any cosmetic work; KEV blocks release.

Read the full file on GitHub · 59 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.

12d ago First seen · 59 lines · 75 tokens per session scan A 558a6b79065a

Subscribe to this mod's changes

cve-zero-day-scanner is a skill published in the GitHub repository ashermahonin/agentic-skills (10 stars, last pushed 19d ago), licensed MIT. It adds 75 tokens to every session and 823 once invoked, about $0.0004 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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