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@fastify/http-proxy

Open actionable advisories and recorded vendor fixes. This public package view has no inventory attached and cannot establish whether your deployment is affected. A vendor fix never resolves your finding; verify your installed version and the source guidance.

Open advisories

1 actionable advisory, newest first. Withdrawn advisories and news are excluded. Coverage is partial.

  1. Critical, CVSS 9.0npmAmendedPublished

    Fastify's connection header abuse enables stripping of proxy-added headers

    CVE-2026-33805 · GHSA-gwhp-pf74-vj37

    Affected
    • npm @fastify/http-proxy <= 11.4.3
    Fixed in
    11.4.4· Vendor fix available
    Issue
    @fastify/reply-from and @fastify/http-proxy process the client's Connection header after the proxy has added its own headers via rewriteRequestHeaders. This allows attackers to retroactively strip proxy-added headers (like access control or identification headers) from upstream requests by listing them in the Connection header value. This affects applications using these plugins with custom header injection for routing, access control, or security purposes. Details The vulnerability exists in @fastify/reply-from/lib/request.js at lines 128-136 (HTTP/1.1 handler) and lines 191-200 (undici handler). The processing flow is: 1. Client headers are copied including the connection header (@fastify/reply-from/index.js line 91) 2. The proxy adds custom headers via rewriteRequestHeaders (line 151) 3. During request construction, the transport handlers read the client's Connection header and strip any headers listed in it 4. This stripping happens after rewriteRequestHeaders, allowing…

    Recommended action: Upgrade to 11.4.4 or later, then redeploy and verify.A vendor fix does not resolve your finding until you verify it in your own systems.

    Sources:github.com (1)osv.dev (2)Source checked Evidence →