Written against what disclosed bug-bounty reports and public write-ups actually
turn up, and chosen by diffing the existing 245 skills rather than restating
them. Each one is built around the same discipline the harness now enforces:
the client-side discovery is a lead, and the finding is what the SERVER did.
Browser instrumentation and client trust:
- browser_runtime_hooking — hook fetch/XHR/postMessage/storage/WebCrypto at
document_start to find what the client is trusted to decide, then prove the
server accepts the tampered value with an independent read-back.
- prototype_pollution_gadget_hunt — pollution is a precondition, not a finding.
Hunt the gadget with a getter on Object.prototype that breaks into the
debugger, quote it as file:line from the bundle, and prove the end effect.
- js_source_deep_analysis — recover original sources from source maps, extract
the API surface the UI never shows, and pair every client-side discovery with
the server request that confirms or refutes it.
- client_side_path_traversal — the evidence is which URL left the browser, and
it is Low until chained to something otherwise unreachable.
Authentication:
- webauthn_passkey_downgrade — passkeys as a system: the usual finding is a
weaker factor nobody removed, or enrollment needing only a session.
- email_verification_bypass — the gate is normally on the login screen, not the
API; address normalisation is where pre-account-takeover lives.
- jwt_jku_x5u_injection — whether the token gets to choose its own verifier.
Server-side reach and money:
- ssrf_render_pipeline — PDF/screenshot/unfurl renderers browse on the server's
behalf, usually with no egress restrictions and often with JS enabled; the
returned document is the exfiltration channel.
- payment_webhook_forgery — prove the ORDER changed state, not that the
endpoint returned 200; idempotency failures are their own finding.
- presigned_url_abuse — the bug is what the API is willing to SIGN, which is an
IDOR with a cloud signature on top.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
