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backend-api

Designs and reviews HTTP APIs for FastAPI, Express, and NestJS, focusing on contracts, authentication, and error handling.

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Security score

The backend-api skill was audited on May 31, 2026 and we found 9 security issues across 4 threat categories. Review the findings below before installing.

Categories Tested

Security Issues

medium line 306

Template literal with variable interpolation in command context

SourceSKILL.md
306const cached = await cache.get(`idem:${key}`);
medium line 72

Webhook reference - potential data exfiltration

SourceSKILL.md
72- [ ] Write endpoints that may be retried (`POST /payments`, webhook receivers, order creation) define idempotency behavior
medium line 99

Webhook reference - potential data exfiltration

SourceSKILL.md
99- Design idempotency for retries on create, payment, provisioning, and webhook endpoints.
medium line 111

Webhook reference - potential data exfiltration

SourceSKILL.md
111- **Who calls it?** Browser app, mobile app, third-party integrator, internal service, webhook sender
medium line 215

Webhook reference - potential data exfiltration

SourceSKILL.md
215- Check retries and duplicate submissions for create/payment/webhook paths
low line 353

Base64 decode operation

SourceSKILL.md
353expected = base64.urlsafe_b64encode(hmac.new(SECRET, body.encode(), hashlib.sha256).digest()[:8]).rstrip(b"=").decode()
low line 356

Base64 decode operation

SourceSKILL.md
356return json.loads(base64.urlsafe_b64decode(body + "=="))
low line 246

External URL reference

SourceSKILL.md
246"type": "https://api.example.com/errors/insufficient-funds",
low line 281

External URL reference

SourceSKILL.md
281"type": "https://api.example.com/errors/validation",
Scanned on May 31, 2026
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