Security Audit
You have Claude check codebases, APIs and services for security flaws and get source evidence, a priority and the smallest effective fix for each finding.
What is Security Audit?
Security Audit is a skill by Cloudflare that lets Claude check codebases, APIs, services, command line tools, libraries and daemons for security flaws. The skill is defensive and starts from the source code. It looks for weaknesses that break a real trust boundary and gives you evidence from the code, a safe way to reproduce the issue, a priority and the smallest fix that works.
By default the skill only advises. For security questions, focused reviews or digging into single findings, Claude uses the relevant parts of the instructions without creating files. Claude starts the complete process with six phases and a written report only when you explicitly ask for an audit, a pen test or a comprehensive review. If your request is ambiguous, Claude asks one question first.
Code from the project under review follows strict rules. Builds, tests or fuzzers run only in a sandbox without external network access, with an empty environment and fixed resource limits. If any of these controls is missing, the skill runs nothing and marks the point as open. For specific targets it ships its own guides, for example for AI and agent applications, browser code, and cloud and deployment.
Who it is for
Development teams, security leads and consultancies who want to review the source code of services, APIs, libraries or AI applications for vulnerabilities.
Use cases
- Before a release you have a new API checked for gaps in access control and authentication.
- You are building a chatbot or MCP server and want to know whether model output can reach permissions or data it should not.
- For an internal tool you need a complete security report with prioritized findings and concrete fixes.
What Security Audit does
Two operating modes
In guidance mode Claude answers security questions and reviews specific spots. Full audit mode with all six phases and report files starts only when you explicitly ask for it.
Findings need evidence
A finding counts as confirmed only once the affected principal, resource and security outcome are established. If a runtime or deployment fact is missing, the point is marked as needing validation.
Execution only in a sandbox
Project code runs only in isolation: no external network, an empty environment, a read only target and limits on CPU, memory and runtime. Dependencies are not installed.
Guides per attack surface
Separate files cover AI and LLM applications including RAG, agents and MCP, plus browser code, cloud and deployment, and native targets with a focus on memory safety.
Report in full audit mode
In full audit mode Claude creates a report, a findings list, an architecture description and a list of open validation items in a folder outside the project.
Sub-agents with own space
The skill splits work across sub-agents for research and verification. Each gets its own working directory, and only the coordinating agent writes shared files.
Say this to activate the skill
"Check this endpoint for security flaws.""Run a full security audit of this repository.""Is authorization in this module implemented correctly?""Write me a report on the vulnerabilities in this codebase." Install
npx skills add cloudflare/security-audit-skill --skill security-audit
The command installs the original version from the author's repository (Vercel skills CLI, needs Node.js), add -g for all projects. We do not host a copy: updates come straight from the author. Need help with setup? How to install skills →
Checked automatically
- Automated check on 2026-11-01 (revision c1c8a8c): 20 files in the skill folder read by pattern search. It found no hidden characters, no instructions to override rules, no download-and-run and no access to credentials.
Independent checks on skills.sh, as of 1 Nov 2026
| Gen Agent Trust Hub | Pass |
|---|---|
| Socket | Pass |
| Snyk | Warn |
Good to know
- The scanner Snyk has flagged a warning for this repository. Gen Agent Trust Hub and Socket report no issues.
- Without a sandbox that provides every required control, the skill runs no project code. Affected findings then stay marked as needing validation.
- In full audit mode the skill writes report files by default to a folder in your home directory, outside the project under review.
- The skill cannot resolve deployment or runtime facts on its own. You need to verify such points in your own environment.
- One auditor on skills.sh reports a warning (Snyk). Read its notes before bringing the skill into projects with sensitive data.
- The check is an automated pattern search, not a security guarantee, and reads the skill folder only. The command always installs the author's current version; later versions have not been reviewed by us.
Frequently asked questions about Security Audit
What is Security Audit?
Security Audit is a skill by Cloudflare that lets Claude check source code for security flaws. It works defensively, backs every finding with evidence from the code and proposes the smallest effective fix.
How do I install Security Audit?
You install Security Audit with 'npx skills add cloudflare/security-audit-skill --skill security-audit'. After that, Claude uses the skill for security questions or audit requests.
Is Security Audit free?
Yes, according to the repository Security Audit is released under the MIT license and may be used, modified and redistributed freely.
Does Security Audit start a full audit right away?
No, Security Audit only advises by default and creates no files. Claude runs the six phase process with a report only when you explicitly ask for an audit, a pen test or a comprehensive review.
Does Security Audit touch live systems?
No, Security Audit only reads source code and runs project code exclusively in an isolated sandbox without network access. According to its instructions it leaves production systems, external services and paid API quota alone.
Who is Security Audit for?
Security Audit suits development teams and security leads who review their own codebases, APIs, libraries or AI applications and need findings with evidence and suggested fixes.
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About this skill
Security Audit comes from cloudflare and is an open-source project maintained by its author and community.
Author: cloudflare / github.com. Source: github.com/cloudflare/security-audit-skill/tree/main/skills/security-audit. Licence: MIT.
Curated by Collective Brain, an AI and automation digital agency from Hamburg, together with WhiteFox Automations. More vetted skills in the skills catalog.
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