api-gateway-bypass

Tests API gateway access control bypasses via path normalization and method override discrepancies.

2|1|Updated Aug 28, 2026
One-click install
npx skills add https://github.com/lycheer1126/xs-bigdan --skill api-gateway-bypass-lycheer1126
Or copy as Structured Prompt for Agent▼
Please help me install this Agent Skill.
Skill: api-gateway-bypass
Source: https://github.com/lycheer1126/xs-bigdan/tree/main/knowledge/skills/api_gateway_bypass
Command: npx skills add https://github.com/lycheer1126/xs-bigdan --skill api-gateway-bypass-lycheer1126

SYSTEM DOCUMENTATION & REQUIREMENTS

What problem does it solve? When an API gateway returns 403 for protected routes, testers need a systematic way to check whether the gateway and backend normalize paths differently, because that mismatch can expose admin APIs to unauthorized access. ## Core Features & Use Cases - Path Normalization Payloads: Provides dot-segment, double-slash, URL-encoding, semicolon, and backslash variants that exploit gateway/backend parsing differences. - Method Override & Version Fallback: Covers X-HTTP-Method-Override headers and legacy API version paths (v1, unversioned) that gateways forget to protect. - Gateway-Specific Techniques: Documents Kong, Nginx, and AWS API Gateway specific bypasses, plus rate-limit evasion and API documentation discovery (swagger.json, /v3/api-docs). - Use Case: During an authorized SRC test, a target returns a Kong-flavored 403 on /api/admin; apply the normalization payload list to find /api/%2e/admin reaches the backend, then confirm with a rejected-vs-bypassed request pair as evidence. ## Quick Start Ask the agent to test the target's 403 API gateway endpoints for path normalization and method override bypasses using this manual.

Frequently Asked Questions about api-gateway-bypass

High-intent search queries and answers about installing and using this skill.

FAQPage Schema
How do I bypass API gateway 403 restrictions?▼

Test path normalization differences between the gateway and backend: try variants like /api/./admin, /api//admin, /api/%2e/admin, and semicolon or backslash forms. If the gateway and backend normalize differently, one variant may reach the protected resource.

How to test HTTP method override headers for access control bypass?▼

Send X-HTTP-Method-Override, X-HTTP-Method, or X-Method-Override headers with values like DELETE or PUT against endpoints where the gateway only blocks certain methods. Some frameworks also accept a ?_method=DELETE URL parameter.

What are common Kong or Nginx API gateway bypass techniques?▼

For Kong, try double slashes and %2f encodings that its router and upstream normalize differently. For Nginx, merge_slashes off lets //admin pass through, and proxy_pass path rewriting can make a blocked location resolve to a different backend route.

Does rate limit bypass with X-Forwarded-For work on API gateways?▼

It works when the backend trusts X-Forwarded-For for rate limiting; rotating the header value resets the counter. Endpoint variants like trailing slashes or case changes also evade per-path counters, but only use this within authorized testing scope.

When should API gateway bypass testing not be used?▼

Only use it on explicitly authorized targets such as SRC-listed scopes or written engagements. Stop after proving reachability of the protected resource, do not pivot to internal networks, and report findings to the program before disclosing reproducible details.