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fix(security): prevent rate limit bypass via X-Forwarded-For spoofing #338

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Merged
Priyanshu-byte-coder merged 1 commit into from
May 19, 2026
+9 −6
Merged

fix(security): prevent rate limit bypass via X-Forwarded-For spoofing #338

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15 changes: 9 additions & 6 deletions src/app/api/public/[username]/route.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -19,12 +19,15 @@ const RATE_LIMIT_REQUESTS = 30;
const RATE_LIMIT_WINDOW_MS = 60 * 1000; // 1 minute

function getRateLimitKey(req: NextRequest): string {
return (
req.headers.get("x-forwarded-for") ||
req.headers.get("x-real-ip") ||
req.ip ||
"unknown"
);
// req.ip is populated by the Next.js / Vercel runtime from the verified
// network-layer source address and cannot be spoofed by the caller.
//
// x-forwarded-for is intentionally excluded here: it is a plain request
// header that any client can set to an arbitrary value. Trusting it as the
// primary key allows an attacker to rotate the header on every request,
// bypass the per-IP limit entirely, and exhaust the shared GITHUB_TOKEN
// quota (5 000 req/hr), making the endpoint unavailable for all users.
return req.ip || req.headers.get("x-real-ip") || "unknown";
}

function checkRateLimit(ip: string): { allowed: boolean; retryAfter?: number } {
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