Every founder building with Claude, Cursor or Copilot right now is moving faster than any product team could five years ago. What most aren't doing is auditing what got shipped along the way.
That's not a knock on AI-assisted development. It's an observation about incentives: speed is visible, security debt isn't, until it is. The same five vulnerability classes turn up again and again in fast-shipped SaaS products, not because the tooling is bad, but because nobody asked the agent to check for them.
We built a Claude Skill that does exactly that, and we're giving it away.
Why this matters more for AI-built apps, not less
There's a lazy assumption that AI-generated code is either uniformly safer (because it "follows best practice") or uniformly riskier (because "an AI wrote it"). Neither holds up. The real pattern is narrower and more useful: agentic coding tools are very good at making a feature work, and comparatively indifferent to whether that feature can be abused.
A webhook importer that fetches a URL will fetch the URL you asked for. It will also, without being told otherwise, fetch 169.254.169.254 if a user points it there. That's not hypothetical, it's the default behaviour of "fetch this URL" until someone deliberately closes it off.
None of these require a sophisticated attacker. They require a bored one.
The five that keep showing up
ORM-level injection
Dynamic queries built from user input with no allowlist behind them.
Over-exposed API responses
Endpoints that return the whole database record because it was easier than defining a shape.
Server-side request forgery
Any "fetch this for me" feature with no restriction on what "this" can be.
Stored XSS
User content saved once, rendered everywhere, sanitised nowhere.
Permissive CORS
Wildcard origins, sometimes with credentials attached, because it made local development easier.
What we built
A Claude Skill: a structured, five-part audit that runs against a codebase, tests the app after each fix, and produces a single ranked findings report at the end. Not five disconnected chat transcripts. One document, ranked by impact and exploitability, with remediation already applied and a guide for testing what's left.
It closes with a report a technical co-founder can hand to an investor during diligence, or a solo founder can run themselves in an afternoon.
Free download · .zip
The Security Audit Claude Skill
Five-part audit, remediation applied as it goes, one ranked findings report at the end. Unzip into your Claude skills folder and run it against your codebase.
Download the skill (.zip) →Why we're the ones publishing this
We didn't write this checklist to sell a security product. We built Briefly Daily AI on the same stack most of this audience is using, and we ran this exact audit against our own build before we'd trust it with anyone's inbox. Thought leadership that isn't backed by having actually done the thing is just content. This is the thing.
If you're shipping fast, that's the right call. Just make sure speed and security are two separate conversations, not one you're hoping resolves itself.
The short version
Speed and security are two separate conversations, and security can't be one you're hoping resolves itself.