Skill Claude CodeCodex
The sinks and boundaries that belong to no framework: passing input to a shell or an evaluator, letting input choose a filesystem path, validating at a boundary that is not an HTTP request, and handling regulated data (PII, PHI, cardholder data) so it does not spread into paths nobody reviews. Use when generating or…
Skill Claude CodeCodex
Turning a confirmed and fixed finding into a permanent guard: proving the test fails without the fix, asserting the effect and not only the status code, seeding the two principals an authorization test needs, making a timing or out-of-band proof deterministic enough for CI, and keeping the test in a job that can…
Skill Claude CodeCodex
What a function-as-a-service platform changes: an execution environment reused between invocations so /tmp and module globals outlive a request, an event envelope that is attacker-influenced whichever trigger delivered it, encrypted-at-rest configuration that the control-plane API still returns in cleartext, and…
Skill Claude CodeCodex
Server-Side Request Forgery: allowlisting the destination of a server-side fetch, when re-resolution between check and connect matters, redirect and scheme bypasses, parsers that fetch on their own (XXE, SVG, HTML-to-PDF), cloud metadata, and keeping the response from becoming an oracle. Use when fetching a…
Skill Claude CodeCodex
Vet dependencies before they enter the build: typosquats, dependency confusion, malicious packages, known vulnerabilities, unlocked resolution, risky install and build hooks, EOL embedded runtimes, and the authenticity and freshness of your own release channel. Use when adding or upgrading a dependency, reviewing…
Skill Claude CodeCodex
User input reaching a template compiler rather than its context: the source-versus-values distinction, double-render pipelines, template names chosen by the caller, why a template sandbox is a mitigation and not a boundary, minimizing what the render context exposes, and template-driven resource exhaustion. Use when…
Skill Claude CodeCodex
Decide what a design must be true before code exists: naming assets and actors, locating trust boundaries, producing a written (asset, boundary, threat, control, owner) list, recording the assumptions the design rests on, and knowing when a change invalidates the model. Use when scaffolding a new feature, service, or…
Skill Claude CodeCodex
Securing the WebSocket upgrade and the frames after it: Origin validation against Cross-Site WebSocket Hijacking, authenticating the handshake rather than the first message, the ticket pattern for browsers that cannot set headers, per-frame authorization, and resource limits on a connection that stays open. Use when…