Security: fix HTTP rate-limit X-Forwarded-For trust behind reverse proxies#89
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When HTTP_TRUSTED_PROXIES is configured, use X-Real-IP or the rightmost X-Forwarded-For hop instead of the client-controlled leftmost entry. This closes a rate-limit bypass and DoS amplification path behind nginx-style reverse proxies that append the connecting address. Co-authored-by: Alexander Wagner <info@alexanderwagnerdev.com>
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Superseded by #90, which contains this PR's commit plus the clippy Generated by Claude Code |
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Security review (2026-07-17)
One new validated finding was reported and fixed on this branch.
Medium — Spoofed
X-Forwarded-Forbypasses HTTP rate limits behind trusted reverse proxiessrc/rate_limit.rsHTTP_TRUSTED_PROXIESis set (documented Docker/nginx deployment), the limiter used the leftmostX-Forwarded-Forhop. With nginx$proxy_add_x_forwarded_for, that hop is attacker-controlled, so clients could rotate synthetic IPs to bypass per-client buckets and amplify traffic up to the 10,000-entry tracking cap (including fail-closed denial for new legitimate clients).X-Real-IPwhen present; otherwise derive the client IP from the rightmostX-Forwarded-Forhop appended by the immediate trusted proxy. Added regression tests and clarified.env.example/ config docs.Closes #88
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